fix: complete image pipeline - rotation, URL, preview

- Add rotation_degrees parameter to ImageProcessor.process_photo()
- Pass rotation through _auto_save_photo_from_extraction() to processor
- Allow no-crop fallback when crop_bounds is None
- Add buildPhotoUrl() helper to resolve backend URLs correctly
- Update frontend components to use backend URL for image sources
- Replace Use/Skip Photo buttons with checkbox in AI extraction UI
- Add images/ to .gitignore to prevent accidental commits

Addresses: rotation never applied, image 404s (relative to Next.js not backend), preview blank in edit form

.gitignore

@@ -148,6 +148,7 @@ backend/.env.test
 # Test images uploaded during development
 _images.tests/
 _images/
+images/
 
 # ── Local AI Tooling & Persistent Paths ──────────────────────
 .tool_paths