feat: unified photo provider abstraction layer (#584)

Introduce trek_photos as central photo registry. Frontend uses
/api/photos/:id/:kind instead of provider-specific URLs. Adding
a new photo provider is now backend-only work.

- New trek_photos table (migration 98) with photo_id FK in
  trip_photos and journey_photos
- Unified /api/photos/:id/thumbnail|original|info endpoint
- photoResolverService for central resolution and streaming
- ProviderPicker: add "All Photos" tab, rename tabs, fix i18n
- Localize all hardcoded strings in JourneyDetailPage (14 langs)
- Fix date formatting to use browser locale instead of hardcoded 'en'
- Journey stats as styled tile cards

server/src/app.ts

@@ -36,6 +36,7 @@ import { oauthPublicRouter, oauthApiRouter } from './routes/oauth';
 import vacayRoutes from './routes/vacay';
 import atlasRoutes from './routes/atlas';
 import memoriesRoutes from './routes/memories/unified';
+import photoRoutes from './routes/photos';
 import notificationRoutes from './routes/notifications';
 import shareRoutes from './routes/share';
 import journeyRoutes from './routes/journey';
@@ -265,6 +266,7 @@ export function createApp(): express.Application {
   app.use('/api/journeys', journeyRoutes);
   app.use('/api/public/journey', journeyPublicRoutes);
   app.use('/api/integrations/memories', memoriesRoutes);
+  app.use('/api/photos', photoRoutes);
   app.use('/api/maps', mapsRoutes);
   app.use('/api/weather', weatherRoutes);
   app.use('/api/settings', settingsRoutes);