feat: per-app initial scale config

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

@@ -8,10 +8,11 @@ import top.yeij.hearth.webapp.Tab
 // multi-WebView lifecycle, visibility, and navigation, and syncing tab state
 // back to the desktop H5 topbar
 interface WebAppHost {
-    // 创建内容 WebView 加载 url 并显示（已存在则切换到该标签）；ua 为清单声明的 UA
+    // 创建内容 WebView 加载 url 并显示（已存在则切换到该标签）；ua 为清单声明的 UA，
+    // scale 为清单声明的初始缩放百分比（可为 null）
     // Create a content WebView loading url and show it (switch if already open);
-    // ua is the UA declared in the manifest
-    fun openWebView(id: String, url: String, ua: String?)
+    // ua is the manifest-declared UA, scale is the initial zoom percentage (nullable)
+    fun openWebView(id: String, url: String, ua: String?, scale: Int?)
 
     // 销毁对应内容 WebView
     // Destroy the corresponding content WebView