migrate background tasks to celery

crawler/celery_app.py

@@ -0,0 +1,31 @@
+import sys
+from celery import Celery
+from dotenv import load_dotenv
+import os
+
+load_dotenv()
+
+app = Celery(
+    "celery_app",
+    broker=os.getenv("CELERY_BROKER_URL", "redis://localhost:6379/0"),
+    backend=os.getenv("CELERY_RESULT_BACKEND", "redis://localhost:6379/1"),
+    include=["tasks.listing_tasks"],
+)
+
+app.conf.update(
+    task_serializer="json",
+    result_serializer="json",
+    accept_content=["json"],
+    timezone="UTC",
+    enable_utc=True,
+)
+
+if __name__ == "__main__":
+    try:
+        with app.connection() as conn:
+            conn.ensure_connection(max_retries=0)
+        print("Broker connection OK")
+        sys.exit(0)
+    except Exception as e:
+        print(f"Broker connection failed: {e}")
+        sys.exit(1)