Fix: Login case-insensitive, Settings zusammengeführt, SVG-Icon, Copyright einzeilig

- Login: Benutzername wird case-insensitiv verglichen (func.lower auf beiden Seiten)
- Benutzer anlegen: Username wird immer lowercase gespeichert
- Einstellungen: Panels "Darstellung", "Ansicht & Raster" und "Ausgeblendete Kalender" zu einem einzigen Panel zusammengeführt
- App-Icon: Emoji 📅 durch plattformunabhängiges Inline-SVG ersetzt
- Copyright: white-space:nowrap +   damit Zeile nie umbricht

frontend/css/app.css

@@ -355,6 +355,7 @@ a { color: var(--primary); text-decoration: none; }
   text-align: center; cursor: pointer;
   background: none; border: none; border-top: 1px solid var(--border);
   transition: color var(--transition);
+  white-space: nowrap;
   position: sticky; bottom: 0;
   background: var(--bg-sidebar);
 }

frontend/index.html

@@ -70,7 +70,7 @@
       <button type="submit" class="btn btn-primary btn-full">Anmelden</button>
     </form>
   </div>
-  <button class="impressum-link" onclick="openImpressum()">© 2026 Scarriffleservices</button>
+  <button class="impressum-link" onclick="openImpressum()">©&nbsp;2026&nbsp;Scarriffleservices</button>
 </div>
 
 <!-- ─── MAIN APP ──────────────────────────────────────────── -->
@@ -83,7 +83,7 @@
         <svg viewBox="0 0 24 24" fill="currentColor"><path d="M3 18h18v-2H3v2zm0-5h18v-2H3v2zm0-7v2h18V6H3z"/></svg>
       </button>
       <div class="topbar-logo">
-        <span>📅</span>
+        <svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><rect x="3" y="4" width="18" height="18" rx="2"/><line x1="16" y1="2" x2="16" y2="6"/><line x1="8" y1="2" x2="8" y2="6"/><line x1="3" y1="10" x2="21" y2="10"/></svg>
         <span class="logo-text">Calendarr</span>
       </div>
     </div>
@@ -170,7 +170,7 @@
           <div id="cal-list-items"></div>
         </div>
       </div>
-      <button class="sidebar-copyright" onclick="openImpressum()">© 2026 Scarriffleservices</button>
+      <button class="sidebar-copyright" onclick="openImpressum()">©&nbsp;2026&nbsp;Scarriffleservices</button>
     </aside>
 
     <!-- MAIN VIEW -->
@@ -390,17 +390,16 @@
     </div>
     <div class="settings-page-body">
       <nav class="settings-nav">
-        <button class="settings-nav-btn active" data-panel="appearance">Darstellung</button>
-        <button class="settings-nav-btn" data-panel="view">Ansicht &amp; Raster</button>
+        <button class="settings-nav-btn active" data-panel="general">Einstellungen</button>
         <button class="settings-nav-btn" data-panel="google">Google Konten</button>
-        <button class="settings-nav-btn" data-panel="hidden">Ausgeblendete Kalender</button>
         <button class="settings-nav-btn hidden" data-panel="users" id="settings-nav-users">Benutzerverwaltung</button>
       </nav>
 
       <div class="settings-panels">
 
-        <!-- Darstellung -->
-        <div class="settings-panel active" id="settings-panel-appearance">
+        <!-- Einstellungen (merged: Darstellung + Ansicht & Raster + Ausgeblendete Kalender) -->
+        <div class="settings-panel active" id="settings-panel-general">
+
           <h4 class="panel-title">Farben</h4>
           <div class="form-group">
             <label>Primärfarbe</label>
@@ -441,11 +440,8 @@
             <button class="contrast-btn" data-val="3"><span class="line-preview" style="border-color:#3a3a52"></span><span class="contrast-lbl">Normal</span></button>
             <button class="contrast-btn" data-val="4"><span class="line-preview" style="border-color:#5a5a78"></span><span class="contrast-lbl">Stark</span></button>
           </div>
-        </div>
 
-        <!-- Ansicht & Raster -->
-        <div class="settings-panel" id="settings-panel-view">
-          <h4 class="panel-title">Kalenderansicht</h4>
+          <h4 class="panel-title" style="margin-top:24px">Kalenderansicht</h4>
           <div class="form-group">
             <label>Standardansicht</label>
             <select id="cfg-default-view">
@@ -477,6 +473,9 @@
             <button class="contrast-btn" data-val="80"><span class="hour-preview">━━━━</span><span class="contrast-lbl">Komfort</span></button>
             <button class="contrast-btn" data-val="100"><span class="hour-preview">━━━━━</span><span class="contrast-lbl">Gross</span></button>
           </div>
+
+          <h4 class="panel-title" style="margin-top:24px">Ausgeblendete Kalender</h4>
+          <div id="hidden-cals-list"><span style="font-size:13px;color:var(--text-3)">Keine ausgeblendeten Kalender</span></div>
         </div>
 
         <!-- Google Konten -->
@@ -485,12 +484,6 @@
           <div id="google-accounts-list"><span style="font-size:13px;color:var(--text-3)">Keine Google-Konten verbunden</span></div>
         </div>
 
-        <!-- Ausgeblendete Kalender -->
-        <div class="settings-panel" id="settings-panel-hidden">
-          <h4 class="panel-title">Ausgeblendete Kalender</h4>
-          <div id="hidden-cals-list"><span style="font-size:13px;color:var(--text-3)">Keine ausgeblendeten Kalender</span></div>
-        </div>
-
         <!-- Benutzerverwaltung -->
         <div class="settings-panel" id="settings-panel-users">
           <h4 class="panel-title">Benutzerverwaltung <span class="badge-admin">Admin</span></h4>