fix: use arq CLI to start worker instead of python -m

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

backend/app/worker.py

@@ -3,7 +3,6 @@
 import logging
 from urllib.parse import urlparse
 
-from arq import cron
 from arq.connections import RedisSettings
 
 from app.config import settings

docker-compose.yml

@@ -56,7 +56,7 @@ services:
       context: ./backend
       dockerfile: Dockerfile
     restart: unless-stopped
-    command: ["python", "-m", "app.worker"]
+    command: ["arq", "app.worker.WorkerSettings"]
     env_file: .env
     environment:
       - DATABASE_URL=${DATABASE_URL:-postgresql+asyncpg://clipforge:changeme_clipforge_2025@postgres:5432/clipforge}