feat: add public profiles list endpoint with search and pagination

- Add new /profiles/ endpoint for listing user profiles
- Support search by username/display name with ordering options
- Include pagination with configurable page size (max 100)
- Add comprehensive OpenAPI schema documentation
- Refactor passkey authentication state management in MFA flow
- Update URL routing and imports for new list_profiles view

This enables user discovery, leaderboards, and friend-finding features
with a publicly accessible, well-documented API endpoint.

backend/apps/api/v1/rides/serializers.py

@@ -306,6 +306,12 @@ class HybridRideSerializer(serializers.ModelSerializer):
     banner_image_url = serializers.SerializerMethodField()
     card_image_url = serializers.SerializerMethodField()
 
+    # Metric unit conversions for frontend (duplicate of imperial fields)
+    coaster_height_meters = serializers.SerializerMethodField()
+    coaster_length_meters = serializers.SerializerMethodField()
+    coaster_speed_kmh = serializers.SerializerMethodField()
+    coaster_max_drop_meters = serializers.SerializerMethodField()
+
     # Computed fields for filtering
     opening_year = serializers.IntegerField(read_only=True)
     search_text = serializers.CharField(read_only=True)
@@ -502,6 +508,47 @@ class HybridRideSerializer(serializers.ModelSerializer):
         """Check if ride has an announced closing date in the future."""
         return obj.is_closing
 
+    # Metric conversions for frontend compatibility
+    @extend_schema_field(serializers.FloatField(allow_null=True))
+    def get_coaster_height_meters(self, obj):
+        """Convert coaster height from feet to meters."""
+        try:
+            if hasattr(obj, "coaster_stats") and obj.coaster_stats and obj.coaster_stats.height_ft:
+                return round(float(obj.coaster_stats.height_ft) * 0.3048, 2)
+            return None
+        except (AttributeError, TypeError):
+            return None
+
+    @extend_schema_field(serializers.FloatField(allow_null=True))
+    def get_coaster_length_meters(self, obj):
+        """Convert coaster length from feet to meters."""
+        try:
+            if hasattr(obj, "coaster_stats") and obj.coaster_stats and obj.coaster_stats.length_ft:
+                return round(float(obj.coaster_stats.length_ft) * 0.3048, 2)
+            return None
+        except (AttributeError, TypeError):
+            return None
+
+    @extend_schema_field(serializers.FloatField(allow_null=True))
+    def get_coaster_speed_kmh(self, obj):
+        """Convert coaster speed from mph to km/h."""
+        try:
+            if hasattr(obj, "coaster_stats") and obj.coaster_stats and obj.coaster_stats.speed_mph:
+                return round(float(obj.coaster_stats.speed_mph) * 1.60934, 2)
+            return None
+        except (AttributeError, TypeError):
+            return None
+
+    @extend_schema_field(serializers.FloatField(allow_null=True))
+    def get_coaster_max_drop_meters(self, obj):
+        """Convert coaster max drop from feet to meters."""
+        try:
+            if hasattr(obj, "coaster_stats") and obj.coaster_stats and obj.coaster_stats.max_drop_height_ft:
+                return round(float(obj.coaster_stats.max_drop_height_ft) * 0.3048, 2)
+            return None
+        except (AttributeError, TypeError):
+            return None
+
     # Water ride stats fields
     water_wetness_level = serializers.SerializerMethodField()
     water_splash_height_ft = serializers.SerializerMethodField()