AI MODELS & final updates - feat: Implement AI Model Configuration with dynamic pricing and REST API

- Added AIModelConfig model to manage AI model configurations in the database.
- Created serializers and views for AI model configurations, enabling read-only access via REST API.
- Implemented filtering capabilities for model type, provider, and default status in the API.
- Seeded initial data for text and image models, including pricing and capabilities.
- Updated Django Admin interface for managing AI models with enhanced features and bulk actions.
- Added validation methods for model and image size checks.
- Comprehensive migration created to establish the AIModelConfig model and seed initial data.
- Documented implementation and validation results in summary and report files.

backend/igny8_core/modules/billing/serializers.py

@@ -142,3 +142,59 @@ class UsageLimitsSerializer(serializers.Serializer):
     """Serializer for usage limits response"""
     limits: LimitCardSerializer = LimitCardSerializer(many=True)
 
+
+class AIModelConfigSerializer(serializers.Serializer):
+    """
+    Serializer for AI Model Configuration (Read-Only API)
+    Provides model information for frontend dropdowns and displays
+    """
+    model_name = serializers.CharField(read_only=True)
+    display_name = serializers.CharField(read_only=True)
+    model_type = serializers.CharField(read_only=True)
+    provider = serializers.CharField(read_only=True)
+    
+    # Text model fields
+    input_cost_per_1m = serializers.DecimalField(
+        max_digits=10, 
+        decimal_places=4, 
+        read_only=True,
+        allow_null=True
+    )
+    output_cost_per_1m = serializers.DecimalField(
+        max_digits=10, 
+        decimal_places=4, 
+        read_only=True,
+        allow_null=True
+    )
+    context_window = serializers.IntegerField(read_only=True, allow_null=True)
+    max_output_tokens = serializers.IntegerField(read_only=True, allow_null=True)
+    
+    # Image model fields
+    cost_per_image = serializers.DecimalField(
+        max_digits=10, 
+        decimal_places=4, 
+        read_only=True,
+        allow_null=True
+    )
+    valid_sizes = serializers.ListField(read_only=True, allow_null=True)
+    
+    # Capabilities
+    supports_json_mode = serializers.BooleanField(read_only=True)
+    supports_vision = serializers.BooleanField(read_only=True)
+    supports_function_calling = serializers.BooleanField(read_only=True)
+    
+    # Status
+    is_default = serializers.BooleanField(read_only=True)
+    sort_order = serializers.IntegerField(read_only=True)
+    
+    # Computed field
+    pricing_display = serializers.SerializerMethodField()
+    
+    def get_pricing_display(self, obj):
+        """Generate pricing display string based on model type"""
+        if obj.model_type == 'text':
+            return f"${obj.input_cost_per_1m}/{obj.output_cost_per_1m} per 1M"
+        elif obj.model_type == 'image':
+            return f"${obj.cost_per_image} per image"
+        return ""
+