Client-side optimization pipeline with apply-to-J-ID

Backend:
- POST /api/files/J-x/optimize/ applies a browser-processed file: replaces
  every copy (renaming when the extension changes), recomputes MD5, size
  and perceptual hashes, seeds guest visibility; 400 when identical,
  409 when the result matches another item, owner/staff only.

Frontend (no server-side processing by design):
- optimize.worker.ts + pipelines: Mediabunny/WebCodecs for video with a
  prefer-hardware hint and per-browser codec detection; MozJPEG/OxiPNG/
  libwebp (jSquash) for images; gifuct-js+gifenc and UPNG for GIF/APNG.
- OptimizeModal: per-file-type options, original vs processed previews
  with sizes/savings, progress bar with ETA, then Apply (overwrite).
- Optimize button on the library detail for the uploader/staff.

frontend/package.json

@@ -10,13 +10,22 @@
     "preview": "vite preview"
   },
   "dependencies": {
+    "@jsquash/jpeg": "^1.6.0",
+    "@jsquash/oxipng": "^2.3.0",
+    "@jsquash/resize": "^2.1.1",
+    "@jsquash/webp": "^1.5.0",
     "@tanstack/react-query": "^5.103.1",
     "clsx": "^2.1.1",
+    "gifenc": "^1.0.3",
+    "gifuct-js": "^2.1.2",
     "lucide-react": "^1.47.0",
+    "mediabunny": "^1.58.0",
     "react": "^19.2.8",
     "react-dom": "^19.2.8",
     "react-router-dom": "^7.18.4",
     "tailwind-merge": "^3.7.0",
+    "upng-js": "^2.1.0",
+    "wasm-feature-detect": "^1.9.0",
     "zustand": "^5.0.15"
   },
   "devDependencies": {