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/serializers/rides.py

@@ -211,6 +211,18 @@ class RideDetailOutputSerializer(serializers.Serializer):
     # Former names (name history)
     former_names = serializers.SerializerMethodField()
 
+    # Coaster statistics - includes both imperial and metric units for frontend flexibility
+    coaster_statistics = serializers.SerializerMethodField()
+    
+    # Metric unit fields for frontend (converted from imperial)
+    height_meters = serializers.SerializerMethodField()
+    length_meters = serializers.SerializerMethodField()
+    max_speed_kmh = serializers.SerializerMethodField()
+    drop_meters = serializers.SerializerMethodField()
+    
+    # Technical specifications list
+    technical_specifications = serializers.SerializerMethodField()
+
     # URL
     url = serializers.SerializerMethodField()
 
@@ -427,6 +439,99 @@ class RideDetailOutputSerializer(serializers.Serializer):
             for entry in former_names
         ]
 
+    @extend_schema_field(serializers.DictField(allow_null=True))
+    def get_coaster_statistics(self, obj):
+        """Get coaster statistics with both imperial and metric units."""
+        try:
+            if hasattr(obj, "coaster_stats") and obj.coaster_stats:
+                stats = obj.coaster_stats
+                return {
+                    # Imperial units (stored in DB)
+                    "height_ft": float(stats.height_ft) if stats.height_ft else None,
+                    "length_ft": float(stats.length_ft) if stats.length_ft else None,
+                    "speed_mph": float(stats.speed_mph) if stats.speed_mph else None,
+                    "max_drop_height_ft": float(stats.max_drop_height_ft) if stats.max_drop_height_ft else None,
+                    # Metric conversions for frontend
+                    "height_meters": round(float(stats.height_ft) * 0.3048, 2) if stats.height_ft else None,
+                    "length_meters": round(float(stats.length_ft) * 0.3048, 2) if stats.length_ft else None,
+                    "max_speed_kmh": round(float(stats.speed_mph) * 1.60934, 2) if stats.speed_mph else None,
+                    "drop_meters": round(float(stats.max_drop_height_ft) * 0.3048, 2) if stats.max_drop_height_ft else None,
+                    # Other stats
+                    "inversions": stats.inversions,
+                    "ride_time_seconds": stats.ride_time_seconds,
+                    "track_type": stats.track_type,
+                    "track_material": stats.track_material,
+                    "roller_coaster_type": stats.roller_coaster_type,
+                    "propulsion_system": stats.propulsion_system,
+                    "train_style": stats.train_style,
+                    "trains_count": stats.trains_count,
+                    "cars_per_train": stats.cars_per_train,
+                    "seats_per_car": stats.seats_per_car,
+                }
+        except AttributeError:
+            pass
+        return None
+
+    @extend_schema_field(serializers.FloatField(allow_null=True))
+    def get_height_meters(self, obj):
+        """Convert height from feet to meters for frontend."""
+        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)
+        except (AttributeError, TypeError):
+            pass
+        return None
+
+    @extend_schema_field(serializers.FloatField(allow_null=True))
+    def get_length_meters(self, obj):
+        """Convert length from feet to meters for frontend."""
+        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)
+        except (AttributeError, TypeError):
+            pass
+        return None
+
+    @extend_schema_field(serializers.FloatField(allow_null=True))
+    def get_max_speed_kmh(self, obj):
+        """Convert max speed from mph to km/h for frontend."""
+        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)
+        except (AttributeError, TypeError):
+            pass
+        return None
+
+    @extend_schema_field(serializers.FloatField(allow_null=True))
+    def get_drop_meters(self, obj):
+        """Convert drop height from feet to meters for frontend."""
+        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)
+        except (AttributeError, TypeError):
+            pass
+        return None
+
+    @extend_schema_field(serializers.ListField(child=serializers.DictField()))
+    def get_technical_specifications(self, obj):
+        """Get technical specifications list for this ride."""
+        try:
+            from apps.rides.models import RideTechnicalSpec
+            
+            specs = RideTechnicalSpec.objects.filter(ride=obj).order_by("category", "name")
+            return [
+                {
+                    "id": spec.id,
+                    "name": spec.name,
+                    "value": spec.value,
+                    "unit": spec.unit,
+                    "category": spec.category,
+                }
+                for spec in specs
+            ]
+        except Exception:
+            return []
+
 
 class RideImageSettingsInputSerializer(serializers.Serializer):
     """Input serializer for setting ride banner and card images."""