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/java/top/yeij/hearth/webview/WebViewManager.kt

@@ -10,6 +10,9 @@ class WebViewManager(private val activity: Activity) {
     @SuppressLint("SetJavaScriptEnabled")
     fun attach(bridge: JsBridge): WebView {
         val webView = WebView(activity)
+        // 透明背景，露出原生壁纸
+        // Transparent background to reveal native wallpaper
+        webView.setBackgroundColor(android.graphics.Color.TRANSPARENT)
         webView.settings.apply {
             javaScriptEnabled = true
             useWideViewPort = true