feat(frontend): add frontend-v2 modular architecture (Task 17)

- React 19 + TypeScript + Vite
- Module registration mechanism with dynamic loading
- Permission management system (basic/advanced/premium)
- Route guards for access control
- Error boundaries for module isolation
- 6 business module placeholders (AIA/ASL/PKB/DC/SSA/ST)
- Top navigation layout
- Tailwind CSS 3 + Ant Design 5

frontend-v2/src/shared/components/Placeholder.tsx

@@ -0,0 +1,48 @@
+import { Result, Button } from 'antd'
+import { useNavigate } from 'react-router-dom'
+import { RocketOutlined } from '@ant-design/icons'
+
+interface PlaceholderProps {
+  title?: string
+  description?: string
+  moduleName?: string
+}
+
+const Placeholder = ({ 
+  title = '功能开发中', 
+  description = '该模块正在规划和开发中，敬请期待',
+  moduleName 
+}: PlaceholderProps) => {
+  const navigate = useNavigate()
+
+  return (
+    <div className="flex-1 flex items-center justify-center bg-gray-50">
+      <Result
+        icon={<RocketOutlined style={{ fontSize: 72, color: '#1890ff' }} />}
+        title={<span className="text-2xl">{title}</span>}
+        subTitle={
+          <div className="space-y-2">
+            <p className="text-gray-600">{description}</p>
+            {moduleName && (
+              <p className="text-sm text-gray-400">
+                模块名称：{moduleName}
+              </p>
+            )}
+          </div>
+        }
+        extra={
+          <Button type="primary" onClick={() => navigate('/')}>
+            返回首页
+          </Button>
+        }
+      />
+    </div>
+  )
+}
+
+export default Placeholder
+
+
+
+
+