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/draft_run_service.py

@@ -1299,10 +1299,23 @@ class AgentRunService:
                 "history_files": {}
             }
             if files:
+                from app.models.file_metadata_model import FileMetadata
                 for f in files:
+                    name, size = f.name, f.size
+                    if f.transfer_method.value == "local_file" and f.upload_file_id and (not name or not size):
+                        meta = self.db.query(FileMetadata).filter(
+                            FileMetadata.id == f.upload_file_id,
+                            FileMetadata.status == "completed"
+                        ).first()
+                        if meta:
+                            name = name or meta.file_name
+                            size = size or meta.file_size
                     human_meta["files"].append({
                         "type": f.type,
-                        "url": f.url
+                        "url": f.url,
+                        "file_type": f.file_type,
+                        "name": name,
+                        "size": size
                     })
 
             # 保存 history_files，包含 provider 和 is_omni 信息