feat(frontend): 对接后端统一响应格式，增强错误处理

- 新增 types/api.ts，定义 ApiResponse/PaginatedData 泛型类型和业务错误码常量
- 增强 request.ts 拦截器：提取后端错误信息、映射 HTTP 状态码和业务错误码为中文提示
- 为 auth/audit/subsystem API 添加泛型返回类型
- 为各视图添加 try/catch 防止未处理的 Promise 拒绝

frontend/src/views/audit/LoginAudit.vue

@@ -33,9 +33,13 @@ const auditData = ref<LoginAudit[]>([])
 const total = ref(0)
 
 const fetchData = async () => {
-  const { data } = await auditApi.getLoginAudit()
-  auditData.value = data.items
-  total.value = data.total
+  try {
+    const { data } = await auditApi.getLoginAudit()
+    auditData.value = data.items
+    total.value = data.total
+  } catch {
+    // 错误已由 request 拦截器统一处理
+  }
 }
 
 const refresh = () => {