Based on the git diff provided, here's a concise and descriptive commit message:

feat: add passkey authentication and enhance user preferences

- Add passkey login security event type with fingerprint icon
- Include request and site context in email confirmation for backend
- Add user_id exact match filter to prevent incorrect user lookups
- Enable PATCH method for updating user preferences via API
- Add moderation_preferences support to user settings
- Optimize ticket queries with select_related and prefetch_related

This commit introduces passkey authentication tracking, improves user
profile filtering accuracy, and extends the preferences API to support
updates. Query optimizations reduce database hits for ticket listings.

backend/apps/rides/signals.py

@@ -6,7 +6,7 @@ from django.utils import timezone
 
 from apps.core.utils import capture_and_log
 
-from .models import Ride
+from .models import Ride, RideSubType
 
 logger = logging.getLogger(__name__)
 
@@ -286,3 +286,59 @@ def track_ride_name_changes(sender, instance, **kwargs):
     except Exception as e:
         logger.exception(f"Failed to track name change for ride {instance.pk}: {e}")
 
+
+# =============================================================================
+# Auto-Create Ride Sub-Types on Ride Save
+# =============================================================================
+
+
+@receiver(post_save, sender=Ride)
+def auto_create_ride_sub_type(sender, instance, created, **kwargs):
+    """
+    Automatically create a RideSubType entry when a ride is saved with a new sub-type value.
+    
+    This integrates with the submission pipeline - when a ride submission with a new
+    ride_sub_type value is approved, the sub-type automatically gets added to the
+    lookup table for future autocomplete suggestions.
+    
+    Args:
+        sender: The Ride model class.
+        instance: The Ride instance that was saved.
+        created: Whether this is a new ride (not used, we check sub-types for all saves).
+    """
+    # Skip if no ride_sub_type is set
+    if not instance.ride_sub_type or not instance.ride_sub_type.strip():
+        return
+    
+    # Skip if no category is set (can't categorize the sub-type)
+    if not instance.category:
+        return
+    
+    ride_sub_type_value = instance.ride_sub_type.strip()
+    
+    try:
+        # Check if this sub-type already exists for this category
+        existing = RideSubType.objects.filter(
+            name__iexact=ride_sub_type_value,
+            category=instance.category
+        ).exists()
+        
+        if not existing:
+            # Create the new sub-type entry
+            RideSubType.objects.create(
+                name=ride_sub_type_value,
+                category=instance.category,
+                description=f"Auto-created from ride: {instance.name}",
+                created_by=getattr(instance, 'created_by', None),
+            )
+            logger.info(
+                f"Auto-created RideSubType '{ride_sub_type_value}' for category "
+                f"'{instance.category}' from ride '{instance.name}'"
+            )
+    except Exception as e:
+        # Non-critical error - log but don't fail the ride save
+        logger.warning(
+            f"Failed to auto-create RideSubType for ride {instance.pk}: {e}"
+        )
+
+