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/app_chat_service.py

@@ -26,6 +26,7 @@ from app.services.model_service import ModelApiKeyService
 from app.services.multi_agent_orchestrator import MultiAgentOrchestrator
 from app.services.multimodal_service import MultimodalService
 from app.services.workflow_service import WorkflowService
+from app.models.file_metadata_model import FileMetadata
 
 logger = get_business_logger()
 
@@ -219,10 +220,21 @@ class AppChatService:
         }
         if files:
             for f in files:
-                # url = await MultimodalService(self.db).get_file_url(f)
+                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,
+                    "name": name,
+                    "size": size,
+                    "file_type": f.file_type,
                 })
 
         if processed_files:
@@ -510,9 +522,21 @@ class AppChatService:
 
             if files:
                 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,
+                        "name": name,
+                        "size": size,
+                        "file_type": f.file_type,
                     })
             if processed_files:
                 human_meta["history_files"] = {