feat(storage): migrate file storage from local disk to MinIO

Replace local filesystem-based image storage with MinIO S3-compatible
object storage. All upload, serve, delete, and list operations now use
the MinIO bucket defined in MINIO_* env vars.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -35,6 +35,7 @@
     "framer-motion": "^12.4.1",
     "get-port": "^7.1.0",
     "lodash": "^4.17.21",
+    "minio": "^8.0.7",
     "motion": "^12.4.1",
     "nanoid": "^5.1.0",
     "next": "15.1.6",