feat: page preload, card grid span, wallpaper into webview for glass blur

app/src/main/java/top/yeij/hearth/webview/JsBridge.kt

@@ -36,6 +36,14 @@ interface ServerUrlProvider {
     fun setServerUrl(url: String)
 }
 
+// 壁纸提供接口：由 MainActivity 实现（WallpaperManager 转 base64），
+// 让壁纸进入 WebView 内部，backdrop-filter 玻璃才能模糊到壁纸
+// Wallpaper provider implemented by MainActivity (WallpaperManager -> base64), so the
+// wallpaper lives inside the WebView and the glass backdrop-filter can blur it
+interface WallpaperProvider {
+    fun getWallpaperBase64(): String
+}
+
 class JsBridge(
     private val deviceWidthPx: Int,
     private val deviceHeightPx: Int,
@@ -58,6 +66,9 @@ class JsBridge(
     // 服务器地址存储接口
     // Server URL storage provider
     private val serverUrl: ServerUrlProvider? = null,
+    // 壁纸提供接口（base64）
+    // Wallpaper provider (base64)
+    private val wallpaper: WallpaperProvider? = null,
 ) {
     private val gson = com.google.gson.Gson()
 
@@ -270,6 +281,11 @@ class JsBridge(
         serverUrl?.setServerUrl(url)
     }
 
+    // 返回壁纸 base64（data URI，未接入返回空字符串）
+    // Return the wallpaper base64 (data URI; empty string when not wired)
+    @android.webkit.JavascriptInterface
+    fun getWallpaper(): String = wallpaper?.getWallpaperBase64() ?: ""
+
     // 重新拉取 webAPP 清单 + 卡片目录，返回 { count }
     // Re-fetch the webAPP manifest + card catalog, return { count }
     @android.webkit.JavascriptInterface