feat(backend): storage trash with seven day retention, trashed files are not fetched again automatically

backend/src/api/routers/media.py

@@ -54,7 +54,7 @@ async def serve_media_version(
     download: Download = False,
 ) -> FileResponse:
     version = await get_media_version(pool, version_id)
-    if version is None:
+    if version is None or not storage.exists(version.storage_key):
         raise HTTPException(status_code=404, detail="media version not found")
     headers = IMMUTABLE_HEADERS
     if download:
@@ -96,6 +96,8 @@ async def serve_media(
             status_code=409,
             detail="media not downloaded; enqueue fetch via POST /api/media/fetch",
         )
+    if not storage.exists(media.storage_key):
+        raise HTTPException(status_code=404, detail="media file is missing")
     headers = DAY_HEADERS
     if download:
         headers = _attachment(headers, media.file_name or f"media_{media_id}")