fix: WorkflowRunDetailApi created_at、finished_at types changed to timestamps (#16821)

api/controllers/service_api/app/workflow.py

 from extensions.ext_database import db
 from fields.workflow_app_log_fields import workflow_app_log_pagination_fields
 from libs import helper
+from libs.helper import TimestampField
 from models.model import App, AppMode, EndUser
 from models.workflow import WorkflowRun, WorkflowRunStatus
 from services.app_generate_service import AppGenerateService
     "error": fields.String,
     "total_steps": fields.Integer,
     "total_tokens": fields.Integer,
-    "created_at": fields.DateTime,
-    "finished_at": fields.DateTime,
+    "created_at": TimestampField,
+    "finished_at": TimestampField,
     "elapsed_time": fields.Float,
 }
 

web/app/components/develop/template/template_workflow.en.mdx

         "error": null,
         "total_steps": 3,
         "total_tokens": 0,
-        "created_at": "Thu, 18 Jul 2024 03:17:40 -0000",
-        "finished_at": "Thu, 18 Jul 2024 03:18:10 -0000",
+        "created_at": 1705407629,
+        "finished_at": 1727807631,
         "elapsed_time": 30.098514399956912
     }
     ```

web/app/components/develop/template/template_workflow.ja.mdx

         "error": null,
         "total_steps": 3,
         "total_tokens": 0,
-        "created_at": "Thu, 18 Jul 2024 03:17:40 -0000",
-        "finished_at": "Thu, 18 Jul 2024 03:18:10 -0000",
+        "created_at": 1705407629,
+        "finished_at": 1727807631,
         "elapsed_time": 30.098514399956912
     }
     ```

web/app/components/develop/template/template_workflow.zh.mdx

         "error": null,
         "total_steps": 3,
         "total_tokens": 0,
-        "created_at": "Thu, 18 Jul 2024 03:17:40 -0000",
-        "finished_at": "Thu, 18 Jul 2024 03:18:10 -0000",
+        "created_at": 1705407629,
+        "finished_at": 1727807631,
         "elapsed_time": 30.098514399956912
     }
     ```