feat(admin): external media import modal + thumbnail fixes for reference events\n\n- Photos tab: replace inline external folder picker with a modal opened via "Import from External Folder" button next to "Upload Photos"; add info that all pictures in the selected folder will be imported.\n- Admin thumbnails: align list endpoint to /api/admin/photos/:eventId/photos and always return thumbnail_url to trigger on-demand generation; normalize external paths to avoid duplicated folder segments (e.g., individual/individual) that broke resolver; improve thumbnail logging.\n- Use authenticated image fetching on admin feedback pages to prevent 401s in automation.\n- i18n: add backup.external.warning strings; complete German backup/restore coverage; add common keys (notSet, of, up, select, selected).\n- Docs: add Local (npm) setup for EXTERNAL_MEDIA_ROOT in deployment guide.\n\nRefs #17 – gallery feature request: https://github.com/the-luap/picpeak/issues/17

frontend/src/services/photos.service.ts

@@ -45,7 +45,8 @@ class PhotosService {
     }
     
     const queryString = params.toString();
-    const url = `/admin/events/${eventId}/photos${queryString ? `?${queryString}` : ''}`;
+    // Use admin photos router for listing to ensure URL alignment with media/thumbnail endpoints
+    const url = `/admin/photos/${eventId}/photos${queryString ? `?${queryString}` : ''}`;
     
     const response = await api.get(url);
     
@@ -96,4 +97,4 @@ class PhotosService {
   }
 }
 
-export const photosService = new PhotosService();
+export const photosService = new PhotosService();