feat(frontend): 打磨管理台交互体验与可访问性

- 优化 Dashboard、Bindings、Logs、Settings 的布局、筛选区与信息层级
- 增加筛选状态同步、未保存提醒、运行时反馈和趋势表视图
- 补充跳转主内容、aria live、键盘导航与移动端触控细节

frontend/src/composables/useAsyncAction.js

@@ -2,16 +2,25 @@ import { ref } from 'vue'
 import { ElMessage } from 'element-plus'
 
 import { humanizeError } from '../api'
+import { announcePolite } from '../utils/liveRegion'
 
 export function useAsyncAction() {
   const loading = ref(false)
+  const errorMessage = ref('')
+
+  function clearError() {
+    errorMessage.value = ''
+  }
 
   async function run(task, fallbackMessage) {
     loading.value = true
+    clearError()
     try {
       return await task()
     } catch (error) {
-      ElMessage.error(humanizeError(error, fallbackMessage))
+      errorMessage.value = humanizeError(error, fallbackMessage)
+      announcePolite(errorMessage.value)
+      ElMessage.error(errorMessage.value)
       throw error
     } finally {
       loading.value = false
@@ -19,6 +28,8 @@ export function useAsyncAction() {
   }
 
   return {
+    clearError,
+    errorMessage,
     loading,
     run,
   }