fix: Handle nested JSON structures in VLM response parsing

pixelle_video/services/quality/character_analyzer.py

@@ -242,13 +242,43 @@ Output ONLY the JSON object, no additional text."""
                 logger.warning(f"No JSON found in response, trying direct parse")
                 data = json.loads(cleaned)
             
+            # Handle nested JSON structures - flatten to strings
+            appearance = data.get("appearance_description", "")
+            if isinstance(appearance, dict):
+                # Flatten nested object to descriptive string
+                parts = []
+                for key, value in appearance.items():
+                    if isinstance(value, dict):
+                        # Further nested (e.g., hair: {color, length, style})
+                        details = ", ".join(f"{k}: {v}" for k, v in value.items())
+                        parts.append(f"{key} ({details})")
+                    else:
+                        parts.append(f"{key}: {value}")
+                appearance = "; ".join(parts)
+            
+            clothing = data.get("clothing_description", "")
+            if isinstance(clothing, dict):
+                # Flatten nested clothing description
+                parts = []
+                for person, items in clothing.items():
+                    if isinstance(items, dict):
+                        details = ", ".join(f"{k}: {v}" for k, v in items.items())
+                        parts.append(f"{person} ({details})")
+                    else:
+                        parts.append(f"{person}: {items}")
+                clothing = "; ".join(parts)
+            
+            distinctive = data.get("distinctive_features", [])
+            if not isinstance(distinctive, list):
+                distinctive = [str(distinctive)]
+            
             result = CharacterAnalysisResult(
-                appearance_description=data.get("appearance_description", ""),
-                clothing_description=data.get("clothing_description", ""),
-                distinctive_features=data.get("distinctive_features", []),
+                appearance_description=appearance,
+                clothing_description=clothing,
+                distinctive_features=distinctive,
             )
             
-            logger.info(f"Character analysis extracted: {result.appearance_description[:80]}...")
+            logger.info(f"Character analysis extracted: {result.appearance_description[:80] if result.appearance_description else 'empty'}...")
             return result
             
         except (json.JSONDecodeError, KeyError) as e: