feat: Einstellungen in Kapitel (Profil/Darstellung/Ansicht/Kalender)

- Settings-Sidebar mit Kapiteln: Profil, Darstellung, Ansicht, Kalender,
  Benutzerverwaltung (statt eines langen "Darstellung"-Panels).
- Neues "Profil"-Kapitel: Anzeigename + Login-Name ändern, E-Mail, plus
  Privatsphäre (private Sichtbarkeit) und "Für Gruppen sichtbarer Kalender".
- "Konten" → "Kalender" umbenannt. Version v39.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/js/calendar.js

@@ -2553,6 +2553,14 @@ function openSettingsModal() {
   document.getElementById('cfg-private-visibility').value = s.private_event_visibility || 'busy';
   renderGroupVisibleList(s.group_visible_calendar_id);
 
+  // Profile chapter: name (from cached user) + email (fresh from /profile).
+  const pu = JSON.parse(localStorage.getItem('user') || '{}');
+  document.getElementById('cfg-display-name').value = pu.display_name || pu.username || '';
+  document.getElementById('cfg-login-name').value = pu.username || '';
+  api.get('/profile/').then(p => {
+    document.getElementById('cfg-email').value = p.email || '';
+  }).catch(() => {});
+
   // Set active contrast/hour-height buttons
   [
     { id: 'cfg-text-contrast', val: s.text_contrast || 3 },
@@ -3003,6 +3011,29 @@ function bindSettingsModal() {
     } catch (e) { showToast(e.message, true); }
   };
 
+  // Profile chapter save (name/login/email → /profile, separate from settings).
+  const profileSaveBtn = document.getElementById('cfg-profile-save');
+  if (profileSaveBtn) profileSaveBtn.onclick = async () => {
+    const email = document.getElementById('cfg-email').value.trim();
+    const displayName = document.getElementById('cfg-display-name').value.trim();
+    const loginName = document.getElementById('cfg-login-name').value.trim();
+    const user = JSON.parse(localStorage.getItem('user') || '{}');
+    const body = { email: email || null };
+    if (displayName) body.display_name = displayName;
+    if (loginName && loginName.toLowerCase() !== (user.username || '')) body.username = loginName;
+    try {
+      const res = await api.put('/profile/', body);
+      if (res && res.access_token) localStorage.setItem('token', res.access_token);
+      const updated = { ...user };
+      if (displayName) updated.display_name = displayName;
+      if (body.username) updated.username = body.username.toLowerCase();
+      localStorage.setItem('user', JSON.stringify(updated));
+      const dd = document.getElementById('dropdown-username');
+      if (dd) dd.textContent = updated.display_name || updated.username || 'Benutzer';
+      showToast(t('profile_saved'));
+    } catch (e) { showToast(e.message, true); }
+  };
+
   document.getElementById('settings-save').onclick = async () => {
     const getActive = (id) => {
       const btn = document.querySelector(`#${id} .contrast-btn.active`);

frontend/js/i18n.js

@@ -60,6 +60,9 @@ const translations = {
     // Settings
     settings_title: 'Einstellungen',
     settings_nav_appearance: 'Darstellung',
+    settings_nav_profile: 'Profil',
+    settings_nav_view: 'Ansicht',
+    settings_nav_calendars: 'Kalender',
     settings_nav_google: 'Google Konten',
     settings_nav_users: 'Benutzerverwaltung',
     settings_colors: 'Farben',
@@ -329,6 +332,9 @@ const translations = {
     // Settings
     settings_title: 'Settings',
     settings_nav_appearance: 'Appearance',
+    settings_nav_profile: 'Profile',
+    settings_nav_view: 'View',
+    settings_nav_calendars: 'Calendars',
     settings_nav_google: 'Google Accounts',
     settings_nav_users: 'User Management',
     settings_colors: 'Colors',

frontend/js/version.js

@@ -1,2 +1,2 @@
 // Increment APP_VERSION with every code change
-export const APP_VERSION = 'v38';
+export const APP_VERSION = 'v39';