Add media processing, mine feed filter, and preserve ended streams as videos

- Add ffmpeg-based media asset generation (poster, thumbnail, clip) for previews and videos
- Add GET /media/thumbnails/:filename serving route
- Add filter=mine to feed endpoint for user's own published streams
- Feed response now includes posterUrl, thumbnailUrl, clipUrl
- Deleting an ENDED plan with preview preserves it as a Video record
- Add sourcePlanId to Video schema

package.json

@@ -25,10 +25,13 @@
     "fastify": "^5.2.1",
     "fastify-plugin": "^5.0.1",
     "jose": "^6.0.8",
+    "fluent-ffmpeg": "^2.1.3",
+    "ffmpeg-static": "^5.2.0",
     "undici": "^7.3.0"
   },
   "devDependencies": {
     "@types/node": "^22.13.4",
+    "@types/fluent-ffmpeg": "^2.1.27",
     "@types/ws": "^8.18.1",
     "prisma": "^6.4.1",
     "tsx": "^4.19.3",