feat(entry): 建立 MVVM+data 分层骨架，接入 V2 状态管理与 Navigation 路由

entry/src/main/ets/router/AppRouter.ets

@@ -0,0 +1,30 @@
+/**
+ * 应用级导航封装：持有全局 NavPathStack，页面通过静态方法导航。
+ */
+export class AppRouter {
+  private static stack: NavPathStack | null = null;
+
+  static init(stack: NavPathStack): void {
+    AppRouter.stack = stack;
+  }
+
+  static push(name: string, param?: Object): void {
+    AppRouter.stack?.pushPathByName(name, param);
+  }
+
+  static replace(name: string, param?: Object): void {
+    AppRouter.stack?.replacePathByName(name, param);
+  }
+
+  static pop(): void {
+    AppRouter.stack?.pop();
+  }
+
+  static popToName(name: string): void {
+    AppRouter.stack?.popToName(name);
+  }
+
+  static clear(): void {
+    AppRouter.stack?.clear();
+  }
+}