feat(workflow): refactor iteration runtime to support independent subgraph per task

feat(app): support file metadata in chat messages and DSL app overwrite
- Extended chat message file objects with `name`, `size`, and `file_type` fields across app_chat_service and workflow_service
- Added ability to overwrite existing app configurations via DSL import in app_dsl_service, including type validation and config update logic for AgentConfig, MultiAgentConfig, and WorkflowConfig

api/app/services/workflow_service.py

@@ -957,7 +957,10 @@ class WorkflowService:
                                     for file in message["content"]:
                                         human_meta["files"].append({
                                             "type": file.get("type"),
-                                            "url": file.get("url")
+                                            "url": file.get("url"),
+                                            "file_type": file.get("origin_file_type"),
+                                            "name": file.get("name"),
+                                            "size": file.get("size")
                                         })
                             if message["role"] == "assistant":
                                 assistant_message = message["content"]