feat: add justified layout modes and aspect-ratio-aware mosaic (#146)

- Add Flickr justified-layout and react-photo-album as masonry mode options
- Implement aspect-ratio-aware mosaic layout that dynamically selects
  patterns based on photo orientations to minimize cropping
- Add 9 mosaic pattern types optimized for different orientation combinations
- Add theme customizer options for masonry mode selection (columns/rows/flickr/justified)
- Add i18n translations for new layout options

frontend/package.json

@@ -31,6 +31,7 @@
     "i18next": "^25.3.1",
     "i18next-browser-languagedetector": "^8.2.0",
     "i18next-http-backend": "^3.0.2",
+    "justified-layout": "^4.1.0",
     "linkifyjs": "^4.3.2",
     "lodash": "^4.17.21",
     "lowlight": "^2.9.0",
@@ -42,6 +43,7 @@
     "react-i18next": "^15.6.0",
     "react-image-gallery": "^1.2.11",
     "react-intersection-observer": "^9.4.3",
+    "react-photo-album": "^3.4.0",
     "react-router-dom": "^6.8.0",
     "react-toastify": "11.0.5",
     "tailwind-merge": "^3.3.1"