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 = () => {

frontend/src/views/audit/OpsAudit.vue

@@ -34,9 +34,13 @@ const auditData = ref<OpsAudit[]>([])
 const total = ref(0)
 
 const fetchData = async () => {
-  const { data } = await auditApi.getOpsAudit()
-  auditData.value = data.items
-  total.value = data.total
+  try {
+    const { data } = await auditApi.getOpsAudit()
+    auditData.value = data.items
+    total.value = data.total
+  } catch {
+    // 错误已由 request 拦截器统一处理
+  }
 }
 
 const refresh = () => {

frontend/src/views/auth/Login.vue

@@ -84,8 +84,8 @@ const handleLogin = async () => {
     await login(form.username, form.password)
     ElMessage.success('登录成功')
     router.push('/')
-  } catch (error: any) {
-    ElMessage.error(error.message || '登录失败')
+  } catch {
+    // 错误已由 request 拦截器统一处理
   } finally {
     loading.value = false
   }

frontend/src/views/subsystem/Navigation.vue

@@ -24,8 +24,12 @@ import SubsystemCard from '@/components/SubsystemCard.vue'
 const subsystems = ref<Subsystem[]>([])
 
 onMounted(async () => {
-  const { data } = await subsystemApi.getSubsystems()
-  subsystems.value = data
+  try {
+    const { data } = await subsystemApi.getSubsystems()
+    subsystems.value = data
+  } catch {
+    // 错误已由 request 拦截器统一处理
+  }
 })
 </script>