Add VideoPlayer and LikeButton components with optimistic UI and /server
endpoints for likes. Update media processor to emit WebP and JPEG
fallbacks, store fallback URLs in the DB (migration + snapshot), add
video placeholder asset, and relax CSP media-src for R2.
- uploadToR2 now returns storage path instead of a: full URL. - Generate
signed R2 URLs (24h expiration) for images, thumbnails, and videos in
media processor and when loading finds. - Update CSP to allow
*.r2.cloudflarestorage.com for img-src
