feat: Implement notification system with Apprise integration and credential checks

app/celery_app.py

@@ -18,3 +18,25 @@ celery.conf.task_default_queue = 'document_processor'
 celery.conf.task_routes = {
     "app.tasks.*": {"queue": "document_processor"},
 }
+
+# Task failure notification handler
+from celery.signals import task_failure
+
+@task_failure.connect
+def task_failure_handler(sender=None, task_id=None, exception=None, args=None,
+                        kwargs=None, traceback=None, einfo=None, **kw):
+    """Handler for Celery task failures to send notifications"""
+    if getattr(settings, 'notify_on_task_failure', True):
+        try:
+            # Import here to avoid circular imports
+            from app.utils.notification import notify_celery_failure
+            notify_celery_failure(
+                task_name=sender.name if sender else "Unknown", 
+                task_id=task_id or "N/A",
+                exc=exception, 
+                args=args or [], 
+                kwargs=kwargs or {}
+            )
+        except Exception as e:
+            import logging
+            logging.exception(f"Failed to send task failure notification: {e}")