feat: h5 desktop shell with sidebar and dark mode

- tokens.css/app.css: Miuix dual-color tokens + HyperOS 4 soft-glass rail
- bridge.js/router.js: Promise bridge wrapper + 5-page router with top clock
- index.html: sidebar + 5 page containers
- native wallpaper transparency: Theme.Hearth (showWallpaper + transparent window) + WebView transparent background

app/src/main/assets/h5/js/bridge.js

@@ -0,0 +1,17 @@
+// HearthBridge 原生桥接封装：统一 Promise 调用
+// HearthBridge native bridge wrapper: unified Promise-based calls
+const bridge = {
+  call(method, ...args) {
+    return new Promise((resolve, reject) => {
+      if (!window.HearthBridge || typeof window.HearthBridge[method] !== 'function') {
+        reject(new Error(`bridge method not found: ${method}`));
+        return;
+      }
+      try {
+        resolve(window.HearthBridge[method](...args));
+      } catch (e) {
+        reject(e);
+      }
+    });
+  }
+};