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

client/src/pages/AdminPage.tsx

@@ -192,6 +192,10 @@ export default function AdminPage(): React.ReactElement {
   const [bagTrackingEnabled, setBagTrackingEnabled] = useState<boolean>(false)
   useEffect(() => { adminApi.getBagTracking().then(d => setBagTrackingEnabled(d.enabled)).catch(() => {}) }, [])
 
+  // Collab features
+  const [collabFeatures, setCollabFeatures] = useState<{ chat: boolean; notes: boolean; polls: boolean; whatsnext: boolean }>({ chat: true, notes: true, polls: true, whatsnext: true })
+  useEffect(() => { adminApi.getCollabFeatures().then(d => setCollabFeatures(d)).catch(() => {}) }, [])
+
   // OIDC config
   const [oidcConfig, setOidcConfig] = useState<OidcConfig>({ issuer: '', client_id: '', client_secret: '', client_secret_set: false, display_name: '', discovery_url: '' })
   const [savingOidc, setSavingOidc] = useState<boolean>(false)
@@ -797,6 +801,10 @@ export default function AdminPage(): React.ReactElement {
                 const next = !bagTrackingEnabled
                 setBagTrackingEnabled(next)
                 try { await adminApi.updateBagTracking(next) } catch { setBagTrackingEnabled(!next) }
+              }} collabFeatures={collabFeatures} onToggleCollabFeature={async (key: string) => {
+                const next = { ...collabFeatures, [key]: !collabFeatures[key] }
+                setCollabFeatures(next)
+                try { await adminApi.updateCollabFeatures({ [key]: next[key] }) } catch { setCollabFeatures(collabFeatures) }
               }} />
             </div>
           )}

client/src/pages/TripPlannerPage.tsx

@@ -100,6 +100,7 @@ export default function TripPlannerPage(): React.ReactElement | null {
   }, [undo, lastActionLabel, toast])
 
   const [enabledAddons, setEnabledAddons] = useState<Record<string, boolean>>({ packing: true, budget: true, documents: true, collab: false })
+  const [collabFeatures, setCollabFeatures] = useState<{ chat: boolean; notes: boolean; polls: boolean; whatsnext: boolean }>({ chat: true, notes: true, polls: true, whatsnext: true })
   const [tripAccommodations, setTripAccommodations] = useState<Accommodation[]>([])
   const [allowedFileTypes, setAllowedFileTypes] = useState<string | null>(null)
   const [tripMembers, setTripMembers] = useState<TripMember[]>([])
@@ -116,6 +117,7 @@ export default function TripPlannerPage(): React.ReactElement | null {
       const map = {}
       data.addons.forEach(a => { map[a.id] = true })
       setEnabledAddons({ packing: !!map.packing, budget: !!map.budget, documents: !!map.documents, collab: !!map.collab })
+      if (data.collabFeatures) setCollabFeatures(data.collabFeatures)
     }).catch(() => {})
     authApi.getAppConfig().then(config => {
       if (config.allowed_file_types) setAllowedFileTypes(config.allowed_file_types)
@@ -956,7 +958,7 @@ export default function TripPlannerPage(): React.ReactElement | null {
 
         {activeTab === 'collab' && (
           <div style={{ position: 'absolute', inset: 0, overflow: 'hidden' }}>
-            <CollabPanel tripId={tripId} tripMembers={tripMembers} />
+            <CollabPanel tripId={tripId} tripMembers={tripMembers} collabFeatures={collabFeatures} />
           </div>
         )}
       </div>