feat: PWA-Unterstützung und Mobile-Responsiveness

Macht Calendarr installierbar (Manifest + Service Worker) und auf
Smartphones bedienbar — additive Änderungen, kein Refactoring der
bestehenden Logik, Theme/Variablen unverändert.

PWA:
- frontend/manifest.json (theme #4285f4, bg #0e0e14, name/icons/scope)
- frontend/sw.js (cache-first für Statics, network-first für /api/*)
- frontend/icons/icon-192.png + icon-512.png + icon.svg
- backend/main.py: Routen für /manifest.json, /sw.js, /icons/* damit
  diese Pfade nicht vom SPA-Fallback abgefangen werden
- index.html: manifest-Link, theme-color, apple-touch-icon, apple-* Meta
- app.js: Service-Worker-Registrierung am Ende

Mobile (≤ 768px, additiv am Ende von app.css):
- Sidebar als Overlay mit body.sidebar-open + Backdrop-Element
- View-Switcher horizontal scrollbar wenn er nicht passt
- Monatsansicht zeigt nur farbige Punkte statt Titel
- Wochenansicht reduziert auf Tagesspalte (heute) wenn heute in der
  Woche ist (via :has()), sonst Standard-7-Spalten
- Modale auf voller Breite/Höhe
- Tap-Targets ≥ 44px (icon-btn, btn)
- Kein horizontaler Page-Overflow
- iOS-Safe-Area für Notch/Home-Indicator

Version v2 → v3.

backend/main.py

@@ -115,6 +115,29 @@ FRONTEND_DIR = Path(__file__).parent.parent / "frontend"
 app.mount("/static", StaticFiles(directory=str(FRONTEND_DIR)), name="static")
 
 
+# ── PWA assets that must live at root scope ──────────────
+@app.get("/manifest.json")
+async def pwa_manifest():
+    return FileResponse(str(FRONTEND_DIR / "manifest.json"), media_type="application/manifest+json")
+
+
+@app.get("/sw.js")
+async def pwa_service_worker():
+    return FileResponse(
+        str(FRONTEND_DIR / "sw.js"),
+        media_type="application/javascript",
+        headers={"Service-Worker-Allowed": "/", "Cache-Control": "no-cache"},
+    )
+
+
+@app.get("/icons/{icon_name}")
+async def pwa_icon(icon_name: str):
+    icon_path = FRONTEND_DIR / "icons" / icon_name
+    if not icon_path.exists() or not icon_path.is_file():
+        raise HTTPException(status_code=404, detail="Icon not found")
+    return FileResponse(str(icon_path))
+
+
 @app.get("/{full_path:path}")
 async def spa_fallback(full_path: str):
     if full_path.startswith("api/"):

frontend/css/app.css

@@ -1211,3 +1211,146 @@ a { color: var(--primary); text-decoration: none; }
   margin-top: 12px; padding-top: 10px;
   border-top: 1px solid var(--border-light);
 }
+
+/* ── Mobile / PWA additions ─────────────────────────────────
+   Additive only — does not modify any existing rules above. */
+
+/* Backdrop element exists in DOM but is hidden by default on desktop */
+.sidebar-backdrop { display: none; }
+
+@media (max-width: 768px) {
+  html, body { overflow-x: hidden; max-width: 100vw; }
+
+  /* ── Sidebar slides in as overlay on mobile ─────────────── */
+  .sidebar {
+    position: fixed;
+    top: var(--topbar-h);
+    left: 0;
+    bottom: 0;
+    width: min(85vw, 320px);
+    z-index: 600;
+    transform: translateX(-100%);
+    transition: transform .25s ease;
+    box-shadow: var(--shadow-lg);
+    margin-right: 0 !important;
+  }
+  body.sidebar-open .sidebar { transform: translateX(0); }
+  /* Neutralize the desktop .collapsed shift on mobile so the JS toggle
+     never creates a second hidden state to fight with .sidebar-open */
+  .sidebar.collapsed { transform: translateX(-100%); margin-right: 0 !important; }
+  body.sidebar-open .sidebar.collapsed { transform: translateX(0); }
+
+  .sidebar-backdrop {
+    display: block;
+    position: fixed;
+    inset: 0;
+    background: rgba(0,0,0,.55);
+    z-index: 500;
+    opacity: 0;
+    pointer-events: none;
+    transition: opacity .2s ease;
+  }
+  body.sidebar-open .sidebar-backdrop {
+    opacity: 1;
+    pointer-events: auto;
+  }
+
+  /* ── Topbar tightening + scrollable view switcher ────────── */
+  .topbar { padding: 0 8px; gap: 4px; }
+  .topbar-left { width: auto; flex-shrink: 0; }
+  .topbar-center {
+    min-width: 0;
+    overflow: hidden;
+  }
+  .topbar-center .view-title {
+    font-size: 14px;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+  }
+  .topbar-right {
+    min-width: 0;
+    overflow: hidden;
+  }
+  .view-switcher {
+    overflow-x: auto;
+    overflow-y: hidden;
+    flex-wrap: nowrap;
+    max-width: 100%;
+    -webkit-overflow-scrolling: touch;
+    scrollbar-width: none;
+  }
+  .view-switcher::-webkit-scrollbar { display: none; }
+  .view-switcher .view-btn { flex: 0 0 auto; }
+
+  /* ── 44px minimum tap targets ────────────────────────────── */
+  .icon-btn {
+    min-width: 44px;
+    min-height: 44px;
+  }
+  .btn { min-height: 44px; }
+  .view-switcher .view-btn { min-height: 40px; }
+
+  /* ── Month view: dots instead of full event titles ───────── */
+  .month-span-event {
+    height: 6px !important;
+    line-height: 0 !important;
+    padding: 0 !important;
+    border-radius: 3px !important;
+    font-size: 0 !important;
+    text-overflow: clip !important;
+  }
+  .month-events-overlay { gap: 1px; }
+  .month-more {
+    font-size: 9px;
+    padding: 0 2px;
+  }
+  .cell-day { font-size: 11px; }
+
+  /* ── Week view collapses to single day on mobile when today
+     is in the visible week. Falls back to default 7-col layout
+     for other weeks (use day view there). ──────────────────── */
+  .week-header-row:has(.week-day-header.today) .week-day-header:not(.today) { display: none; }
+  .week-header-row:has(.week-day-header.today) .week-day-header.today { flex: 1 1 100%; width: 100%; }
+  .week-days-col:has(.week-day-col.today) .week-day-col:not(.today) { display: none; }
+  .week-days-col:has(.week-day-col.today) .week-day-col.today { flex: 1 1 100%; width: 100%; }
+  .week-allday-row:has(.week-day-col.today) .week-day-col:not(.today) { display: none; }
+
+  /* ── Modals: full-screen on mobile ───────────────────────── */
+  .modal-overlay { padding: 0; }
+  .modal-card {
+    max-width: 100% !important;
+    width: 100% !important;
+    height: 100%;
+    max-height: 100%;
+    border-radius: 0;
+    display: flex;
+    flex-direction: column;
+  }
+  .modal-body {
+    flex: 1;
+    overflow-y: auto;
+    -webkit-overflow-scrolling: touch;
+  }
+  .modal-footer { flex-shrink: 0; }
+
+  /* Settings page modal: also full-screen */
+  .settings-page-card {
+    max-width: 100% !important;
+    width: 100% !important;
+    height: 100%;
+    max-height: 100%;
+    border-radius: 0;
+  }
+
+  /* ── Misc safety: prevent overflow on flex topbar items ──── */
+  .main-view { width: 100%; min-width: 0; }
+  #view-container { max-width: 100%; overflow-x: hidden; }
+}
+
+/* iOS notch / home-indicator safe areas (PWA standalone) */
+@supports (padding: env(safe-area-inset-top)) {
+  .topbar { padding-top: env(safe-area-inset-top); height: calc(var(--topbar-h) + env(safe-area-inset-top)); }
+  .sidebar { padding-bottom: env(safe-area-inset-bottom); }
+}
+

frontend/icons/icon.svg

@@ -0,0 +1,9 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512">
+  <rect width="512" height="512" fill="#4285f4"/>
+  <g fill="none" stroke="#ffffff" stroke-width="23" stroke-linecap="round" stroke-linejoin="round">
+    <rect x="102" y="154" width="307" height="266" rx="26"/>
+    <line x1="102" y1="234" x2="409" y2="234"/>
+    <line x1="170" y1="103" x2="170" y2="180"/>
+    <line x1="342" y1="103" x2="342" y2="180"/>
+  </g>
+</svg>

frontend/index.html

@@ -2,10 +2,16 @@
 <html lang="de">
 <head>
   <meta charset="UTF-8" />
-  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0, viewport-fit=cover" />
   <!-- APP_VERSION: update here + version.js on every release -->
-  <title>Calendarr v2</title>
+  <title>Calendarr v3</title>
   <link rel="icon" type="image/svg+xml" href="/static/favicon.svg" />
+  <link rel="manifest" href="/manifest.json" />
+  <meta name="theme-color" content="#4285f4" />
+  <meta name="apple-mobile-web-app-capable" content="yes" />
+  <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
+  <meta name="apple-mobile-web-app-title" content="Calendarr" />
+  <link rel="apple-touch-icon" href="/icons/icon-192.png" />
   <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/cropperjs/1.6.2/cropper.min.css" />
   <link rel="stylesheet" href="/static/css/app.css" />
 </head>
@@ -71,7 +77,7 @@
       <button type="submit" class="btn btn-primary btn-full">Anmelden</button>
     </form>
   </div>
-  <button class="impressum-link" onclick="openImpressum()">©&nbsp;2026&nbsp;Scarriffleservices&nbsp;·&nbsp;v2</button>
+  <button class="impressum-link" onclick="openImpressum()">©&nbsp;2026&nbsp;Scarriffleservices&nbsp;·&nbsp;v3</button>
 </div>
 
 <!-- ─── MAIN APP ──────────────────────────────────────────── -->
@@ -173,8 +179,9 @@
           <div id="cal-list-items"></div>
         </div>
       </div>
-      <button class="sidebar-copyright" onclick="openImpressum()">©&nbsp;2026&nbsp;Scarriffleservices&nbsp;·&nbsp;v2</button>
+      <button class="sidebar-copyright" onclick="openImpressum()">©&nbsp;2026&nbsp;Scarriffleservices&nbsp;·&nbsp;v3</button>
     </aside>
+    <div id="sidebar-backdrop" class="sidebar-backdrop"></div>
 
     <!-- MAIN VIEW -->
     <main class="main-view" id="main-view">
@@ -834,7 +841,7 @@
       <a href="mailto:scarriffleservices@gmail.com">scarriffleservices@gmail.com</a></p>
     </div>
     <div class="modal-footer" style="justify-content:space-between;align-items:center">
-      <span style="font-size:12px;color:var(--text-3)">Calendarr v2</span>
+      <span style="font-size:12px;color:var(--text-3)">Calendarr v3</span>
       <button class="btn btn-ghost" onclick="closeImpressum()">Schliessen</button>
     </div>
   </div>

frontend/js/app.js

@@ -188,3 +188,12 @@ function loadAvatarImage(avatarEl, username) {
 
 // ── Start ─────────────────────────────────────────────────
 boot();
+
+// ── Service Worker registration (PWA) ─────────────────────
+if ('serviceWorker' in navigator) {
+  window.addEventListener('load', () => {
+    navigator.serviceWorker.register('/sw.js', { scope: '/' }).catch(err => {
+      console.warn('SW registration failed:', err);
+    });
+  });
+}

frontend/js/calendar.js

@@ -820,7 +820,10 @@ function bindTopbar() {
 function bindSidebar() {
   document.getElementById('sidebar-toggle').onclick = () => {
     document.getElementById('sidebar').classList.toggle('collapsed');
+    document.body.classList.toggle('sidebar-open'); // mobile slide-in
   };
+  const backdrop = document.getElementById('sidebar-backdrop');
+  if (backdrop) backdrop.onclick = () => document.body.classList.remove('sidebar-open');
 
   // Add calendar dropdown
   const addBtn = document.getElementById('btn-add-cal');

frontend/js/version.js

@@ -1,2 +1,2 @@
 // Increment APP_VERSION with every code change
-export const APP_VERSION = 'v2';
+export const APP_VERSION = 'v3';

frontend/manifest.json

@@ -0,0 +1,30 @@
+{
+  "name": "Calendarr",
+  "short_name": "Calendarr",
+  "start_url": "/",
+  "scope": "/",
+  "display": "standalone",
+  "orientation": "any",
+  "background_color": "#0e0e14",
+  "theme_color": "#4285f4",
+  "icons": [
+    {
+      "src": "/icons/icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icons/icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icons/icon.svg",
+      "sizes": "any",
+      "type": "image/svg+xml",
+      "purpose": "any"
+    }
+  ]
+}

frontend/sw.js

@@ -0,0 +1,86 @@
+// Calendarr Service Worker
+// Cache-first for static assets, network-first for /api/* (graceful offline)
+
+const CACHE_VERSION = 'calendarr-v3';
+const STATIC_ASSETS = [
+  '/',
+  '/index.html',
+  '/manifest.json',
+  '/static/css/app.css',
+  '/static/favicon.svg',
+  '/static/js/app.js',
+  '/static/js/api.js',
+  '/static/js/calendar.js',
+  '/static/js/color-picker.js',
+  '/static/js/date-picker.js',
+  '/static/js/i18n.js',
+  '/static/js/utils.js',
+  '/static/js/version.js',
+  '/static/js/views/agenda.js',
+  '/static/js/views/month.js',
+  '/static/js/views/quarter.js',
+  '/static/js/views/week.js',
+  '/icons/icon-192.png',
+  '/icons/icon-512.png',
+  '/icons/icon.svg',
+];
+
+self.addEventListener('install', event => {
+  event.waitUntil(
+    caches.open(CACHE_VERSION).then(cache =>
+      // Use addAll with a fallback so a single missing file doesn't abort install
+      Promise.all(
+        STATIC_ASSETS.map(url =>
+          cache.add(url).catch(err => console.warn('[SW] skip', url, err))
+        )
+      )
+    ).then(() => self.skipWaiting())
+  );
+});
+
+self.addEventListener('activate', event => {
+  event.waitUntil(
+    caches.keys().then(keys =>
+      Promise.all(keys.filter(k => k !== CACHE_VERSION).map(k => caches.delete(k)))
+    ).then(() => self.clients.claim())
+  );
+});
+
+self.addEventListener('fetch', event => {
+  const req = event.request;
+  if (req.method !== 'GET') return;
+
+  const url = new URL(req.url);
+
+  // Network-first for API routes — fail silently if offline
+  if (url.pathname.startsWith('/api/')) {
+    event.respondWith(
+      fetch(req).catch(() =>
+        new Response(JSON.stringify({ offline: true }), {
+          status: 503,
+          headers: { 'Content-Type': 'application/json' },
+        })
+      )
+    );
+    return;
+  }
+
+  // Cache-first for everything else (static)
+  event.respondWith(
+    caches.match(req).then(cached => {
+      if (cached) return cached;
+      return fetch(req).then(resp => {
+        // Only cache successful, basic-origin responses
+        if (resp && resp.status === 200 && resp.type === 'basic') {
+          const clone = resp.clone();
+          caches.open(CACHE_VERSION).then(c => c.put(req, clone)).catch(() => {});
+        }
+        return resp;
+      }).catch(() => {
+        // Offline fallback for navigation requests
+        if (req.mode === 'navigate') return caches.match('/index.html');
+        return new Response('', { status: 503 });
+      });
+    })
+  );
+});