feat: implement feedback filter for liked/favorited photos (Issue #17)

Implemented Feature Request 1 from github.com/the-luap/picpeak/issues/17:
- Added filter functionality to display only liked or favorited photos
- Integrated feedback filter directly into PhotoFilterBar component
- Implemented responsive design with proper mobile/tablet/desktop layouts
- Filter only shows when feedback is enabled for the gallery
- Added proper count display for liked and favorited photos

Improvements:
- Fixed responsive breakpoints (mobile <768px, tablet 768-1023px, desktop ≥1024px)
- Feedback filter shows inline with categories on desktop with vertical divider
- On mobile/tablet, filter appears below categories to prevent layout issues
- Added horizontal scrolling for category buttons to prevent cut-off

Code cleanup:
- Removed all debug console.log statements from production code
- Removed test route from backend gallery.js
- Cleaned up unnecessary logging in frontend components

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/components/gallery/PhotoFeedback.tsx

@@ -28,7 +28,6 @@ export const PhotoFeedback: React.FC<PhotoFeedbackProps> = ({
     queryKey: ['gallery-feedback-settings', gallerySlug],
     queryFn: async () => {
       const data = await feedbackService.getGalleryFeedbackSettings(gallerySlug);
-      console.log('PhotoFeedback received settings:', data);
       return data;
     },
     staleTime: 5 * 60 * 1000, // Cache for 5 minutes