fix: resolve remaining clippy warnings and improve workflow frontend

- Collapse nested if-let in user_service.rs search filter
- Suppress dead_code warning on ApiDoc struct
- Refactor server routing: nest all routes under /api/v1 prefix
- Simplify health check route path
- Improve workflow ProcessDesigner with edit mode and loading states
- Update workflow pages with enhanced UX
- Add Phase 2 implementation plan document

apps/web/src/pages/workflow/CompletedTasks.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useState } from 'react';
+import { useCallback, useEffect, useState } from 'react';
 import { Table, Tag } from 'antd';
 import type { ColumnsType } from 'antd/es/table';
 import { listCompletedTasks, type TaskInfo } from '../../api/workflowTasks';
@@ -15,7 +15,7 @@ export default function CompletedTasks() {
   const [page, setPage] = useState(1);
   const [loading, setLoading] = useState(false);
 
-  const fetch = async () => {
+  const fetchData = useCallback(async () => {
     setLoading(true);
     try {
       const res = await listCompletedTasks(page, 20);
@@ -24,9 +24,9 @@ export default function CompletedTasks() {
     } finally {
       setLoading(false);
     }
-  };
+  }, [page]);
 
-  useEffect(() => { fetch(); }, [page]);
+  useEffect(() => { fetchData(); }, [fetchData]);
 
   const columns: ColumnsType<TaskInfo> = [
     { title: '任务名称', dataIndex: 'node_name', key: 'node_name' },