fix: Add to_dict method to CharacterMemory for JSON serialization

pixelle_video/services/quality/character_memory.py

@@ -558,6 +558,19 @@ class CharacterMemory:
         self._characters.clear()
         self._name_index.clear()
         logger.info("Character memory cleared")
+    
+    def to_dict(self) -> dict:
+        """Convert to JSON-serializable dictionary"""
+        return {
+            "characters": [char.to_dict() for char in self.characters],
+            "config": {
+                "auto_detect_characters": self.config.auto_detect_characters,
+                "use_llm_detection": self.config.use_llm_detection,
+                "inject_character_prompts": self.config.inject_character_prompts,
+                "use_reference_images": self.config.use_reference_images,
+                "enable_visual_features": self.config.enable_visual_features,
+            }
+        }
 
     @property
     def feature_extractor(self):