feat: collab sub-feature toggles and provider icons

- Add admin toggles for individual collab sections (Chat, Notes,
  Polls, What's Next) stored in app_settings
- CollabPanel adapts layout dynamically: chat always fixed 380px,
  remaining panels share space equally
- Mobile: disabled tabs are hidden
- Add Immich and Synology Photos SVG icons to photo provider toggles
- Add Luggage icon to bag tracking sub-toggle
- API: GET/PUT /admin/collab-features endpoints
- i18n: all 15 languages updated

Closes #604

server/src/services/adminService.ts

@@ -459,6 +459,31 @@ export function updateBagTracking(enabled: boolean) {
   return { enabled: !!enabled };
 }
 
+// ── Collab Features ───────────────────────────────────────────────────────
+
+const COLLAB_FEATURE_KEYS = ['collab_chat_enabled', 'collab_notes_enabled', 'collab_polls_enabled', 'collab_whatsnext_enabled'] as const;
+
+export function getCollabFeatures() {
+  const rows = db.prepare("SELECT key, value FROM app_settings WHERE key IN ('collab_chat_enabled', 'collab_notes_enabled', 'collab_polls_enabled', 'collab_whatsnext_enabled')").all() as { key: string; value: string }[];
+  const map: Record<string, string> = {};
+  for (const r of rows) map[r.key] = r.value;
+  return {
+    chat: map['collab_chat_enabled'] !== 'false',
+    notes: map['collab_notes_enabled'] !== 'false',
+    polls: map['collab_polls_enabled'] !== 'false',
+    whatsnext: map['collab_whatsnext_enabled'] !== 'false',
+  };
+}
+
+export function updateCollabFeatures(features: { chat?: boolean; notes?: boolean; polls?: boolean; whatsnext?: boolean }) {
+  const mapping: Record<string, string> = { chat: 'collab_chat_enabled', notes: 'collab_notes_enabled', polls: 'collab_polls_enabled', whatsnext: 'collab_whatsnext_enabled' };
+  const stmt = db.prepare("INSERT OR REPLACE INTO app_settings (key, value) VALUES (?, ?)");
+  for (const [feat, key] of Object.entries(mapping)) {
+    if (features[feat] !== undefined) stmt.run(key, features[feat] ? 'true' : 'false');
+  }
+  return getCollabFeatures();
+}
+
 // ── Packing Templates ──────────────────────────────────────────────────────
 
 export function listPackingTemplates() {