refactor(views): 重组页面目录并调整路由引用

- 页面按功能归入 dashboard、login、workspace、system、demo、internal
- 数据大屏移入示例目录，错误页、内嵌页与刷新中转移入 internal
- 个人中心与我的通知移入 workspace，统一认证回调移入 login
- 应用中心移入 workspace，菜单组件值 iframe 解析到 internal/iframe
- 在线人数函数更名，未收到推送时显示占位符

src/views/demo/data-screen/composables/useKeepTicking.ts

@@ -0,0 +1,52 @@
+import { onMounted, onUnmounted } from "vue";
+
+/**
+ * 常驻定时器：组件存活期间按固定间隔执行回调，页面隐藏时自动暂停
+ *
+ * @param callback 定时器每次触发时执行的回调
+ * @param interval 间隔毫秒数，默认 3000
+ */
+export function useKeepTicking(callback: () => void, interval = 3000) {
+  /** 定时器是否正在运行 */
+  let ticking = false;
+  /** 定时器标识 */
+  let timerId: ReturnType<typeof setInterval> | null = null;
+
+  const startTicker = () => {
+    if (!ticking) {
+      ticking = true;
+      timerId = setInterval(callback, interval);
+    }
+  };
+
+  const stopTicker = () => {
+    if (ticking) {
+      ticking = false;
+      if (timerId) clearInterval(timerId);
+      timerId = null;
+    }
+  };
+
+  const handleVisibilityChange = () => {
+    if (document.hidden) {
+      stopTicker();
+    } else {
+      startTicker();
+    }
+  };
+
+  onMounted(() => {
+    document.addEventListener("visibilitychange", handleVisibilityChange);
+    startTicker();
+  });
+
+  onUnmounted(() => {
+    document.removeEventListener("visibilitychange", handleVisibilityChange);
+    stopTicker();
+  });
+
+  return {
+    startTicker,
+    stopTicker,
+  };
+}