Fix issue #22: Gallery filter counts disappearing and upload errors

This commit comprehensively addresses the persistent issues reported in #22:

1. Gallery Filter Bug - Counts Disappearing
   - Root cause: Frontend fetched filtered photos from backend, then
     calculated counts from already-filtered data
   - Fix: Always fetch ALL photos, apply filtering client-side only
   - Benefits: Counts always accurate, filters work correctly in combo
   - Changed: frontend/src/components/gallery/GalleryView.tsx:76

2. Upload ENOENT Errors
   - Root cause: /tmp/uploads/ directory assumed to exist
   - Fix: Verify and create temp directory before multer initialization
   - Changed: backend/src/routes/gallery.js:814-825

3. Upload "Not Iterable" Errors
   - Root cause: normalizeFiles() didn't handle null/edge cases
   - Fix: Enhanced error handling with try-catch and graceful degradation
   - Changed: backend/src/services/photoProcessor.js:10-52

4. Enhanced Upload Debugging
   - Added file existence verification before copy operations
   - Improved temp file cleanup (properly handle ENOENT)
   - Comprehensive error logging with full context
   - Changed: backend/src/services/photoProcessor.js:108-233

Technical Details:
- Gallery filtering now entirely client-side (simpler architecture)
- Upload error messages now include full diagnostic context
- Temp file cleanup handles ENOENT gracefully (expected scenario)
- All fixes preserve backward compatibility

Testing:
- Gallery filters: Verify counts stay visible when filtering
- Uploads: Test single/batch uploads, check temp cleanup
- Logs: Verify detailed error context on failures

See ISSUE_22_FIX_SUMMARY.md for complete analysis and testing guide.

Fixes #22

frontend/src/components/gallery/GalleryView.tsx

@@ -71,8 +71,9 @@ export const GalleryView: React.FC<GalleryViewProps> = ({ slug, event }) => {
     setGuestId(storedGuestId);
   }, []);
   
-  // Fetch photos with filter support
-  const { data, isLoading, error, refetch } = useGalleryPhotos(slug, filterType, guestId);
+  // Fetch photos WITHOUT filter (always get all photos, filter on frontend)
+  // This ensures counts are always calculated from the full dataset
+  const { data, isLoading, error, refetch } = useGalleryPhotos(slug, 'all', guestId);
   
   // Set protection level when data is available
   useEffect(() => {