fix: Prevent notification errors from rolling back ticket creation

Add availability check for notifications app to avoid database errors
when the notifications table doesn't exist.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

smoothschedule/tickets/signals.py

@@ -1,4 +1,5 @@
 import logging
+from django.db import transaction
 from django.db.models.signals import post_save
 from django.dispatch import receiver
 from django.utils import timezone
@@ -11,6 +12,24 @@ from smoothschedule.users.models import User
 logger = logging.getLogger(__name__)
 
 
+# Flag to check if notifications app is available
+_notifications_available = None
+
+
+def is_notifications_available():
+    """Check if the notifications app is installed and migrated."""
+    global _notifications_available
+    if _notifications_available is None:
+        try:
+            from notifications.models import Notification
+            # Check if the table exists by doing a simple query
+            Notification.objects.exists()
+            _notifications_available = True
+        except Exception:
+            _notifications_available = False
+    return _notifications_available
+
+
 def send_websocket_notification(group_name, message_data):
     """Safely send a WebSocket notification, handling errors gracefully."""
     try:
@@ -31,6 +50,11 @@ def send_websocket_notification(group_name, message_data):
 
 def create_notification(recipient, actor, verb, action_object, target, data):
     """Safely create a notification, handling import and creation errors."""
+    # Skip notification creation if the notifications app is not available
+    if not is_notifications_available():
+        logger.debug("notifications app not available, skipping notification creation")
+        return
+
     try:
         from notifications.models import Notification
         Notification.objects.create(