fix(workers): worker-level recovery — autoretry on transient errors + tightened sweep (5min) + import_media_file body-wrap so no path leaves rows stuck in 'processing'

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/tasks/download.py

@@ -4,6 +4,7 @@ import asyncio
 from pathlib import Path
 
 from sqlalchemy import select
+from sqlalchemy.exc import DBAPIError, OperationalError
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 
 from ..celery_app import celery
@@ -27,7 +28,18 @@ def _async_session_factory():
     return async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False), engine
 
 
-@celery.task(name="backend.app.tasks.download.download_source", bind=True, acks_late=True)
+@celery.task(
+    name="backend.app.tasks.download.download_source",
+    bind=True,
+    acks_late=True,
+    autoretry_for=(OperationalError, DBAPIError, OSError),
+    retry_backoff=10,
+    retry_backoff_max=120,
+    retry_jitter=True,
+    max_retries=3,
+    soft_time_limit=900,
+    time_limit=1200,
+)
 def download_source(self, source_id: int) -> int:
     """Returns the DownloadEvent.id."""