feat: Enhance AI Knowledge Update webhook handler to validate payload structure and handle empty lists

steps/vmh/webhook/aiknowledge_update_api_step.py

@@ -31,6 +31,24 @@ async def handler(request: ApiRequest, ctx: FlowContext[Any]) -> ApiResponse:
         # Extract payload
         payload = request.body
         
+        # Handle case where payload is a list (e.g., from array-based webhook)
+        if isinstance(payload, list):
+            if not payload:
+                ctx.logger.error("❌ Empty payload list")
+                return ApiResponse(
+                    status=400,
+                    body={'success': False, 'error': 'Empty payload'}
+                )
+            payload = payload[0]  # Take first item
+        
+        # Ensure payload is a dict
+        if not isinstance(payload, dict):
+            ctx.logger.error(f"❌ Invalid payload type: {type(payload)}")
+            return ApiResponse(
+                status=400,
+                body={'success': False, 'error': f'Invalid payload type: {type(payload).__name__}'}
+            )
+        
         # Validate required fields
         knowledge_id = payload.get('entity_id') or payload.get('id')
         entity_type = payload.get('entity_type', 'CAIKnowledge')