feat: wire up album filtering to photo queue

Album selection now controls which photos are displayed.
Uses POST /api/search/random with albumIds filter (Immich v3
compatible) instead of the removed GET /api/albums/{id} assets.

- Add albumIds parameter to fetchRandomAssets/fetchRandomAssetIds
- syncFromAlbums: fetch random assets filtered by selected albums
- syncFromAllPhotos: preserve existing global random behavior
- Album mode reshuffles on exhaustion instead of re-fetching
- 24h resync checks album assetCounts for changes before re-fetch
- requestSync + albums_changed action triggers queue rebuild on save
- timerWakeCycle respects album selection
- Discard stale pre-renders on album change

Co-authored-by: Cursor <cursoragent@cursor.com>

src/web_server.cpp

@@ -272,6 +272,7 @@ void AppWebServer::handlePostAlbumsSelect(AsyncWebServerRequest* request,
     String albumsJson;
     serializeJson(doc["album_ids"], albumsJson);
     _settings->saveField("albums_json", albumsJson.c_str());
+    if (_actionCb) _actionCb("albums_changed");
     request->send(200, "application/json", "{\"ok\":true}");
 }