Phase 8: Server health, album filter, Jinja2 engine, password change

5 features implemented:

1. Server health indicator: green/red/yellow dot on each server card.
   Pings Immich in background on page load. New GET /api/servers/{id}/ping.

2. Album selector filter: search input above album list in tracker form.
   Filters by name as you type (case-insensitive). Shows total count.

3. Album last update time: each album in the selector shows its
   updatedAt date. Backend now returns updatedAt from Immich API.

4. Full Jinja2 template engine in notifier:
   - build_full_context() assembles all ~40 variables from blueprint
   - Common date/location detection across assets
   - Per-asset date/location when they differ
   - Favorite indicator, people formatting, asset list with truncation
   - Video warning for Telegram
   - All template slots from TemplateConfig used contextually

5. Password change: PUT /api/auth/password endpoint (validates current
   password, min 6 chars). UI in sidebar footer with inline form.

Also: Phase 9 plan (Telegram bot management) added.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/server/src/immich_watcher_server/api/servers.py

@@ -126,6 +126,20 @@ async def delete_server(
     await session.commit()
 
 
+@router.get("/{server_id}/ping")
+async def ping_server(
+    server_id: int,
+    user: User = Depends(get_current_user),
+    session: AsyncSession = Depends(get_session),
+):
+    """Check if an Immich server is reachable."""
+    server = await _get_user_server(session, server_id, user.id)
+    async with aiohttp.ClientSession() as http_session:
+        client = ImmichClient(http_session, server.url, server.api_key)
+        ok = await client.ping()
+        return {"online": ok}
+
+
 @router.get("/{server_id}/albums")
 async def list_albums(
     server_id: int,
@@ -143,6 +157,7 @@ async def list_albums(
             "albumName": a.get("albumName"),
             "assetCount": a.get("assetCount", 0),
             "shared": a.get("shared", False),
+            "updatedAt": a.get("updatedAt", ""),
         }
         for a in albums
     ]