选中的更新渠道URL写入配置文件并允许从自定义URL更新脚本仓库 (#1864)

Co-authored-by: 辉鸭蛋 <huiyadanli@gmail.com>

BetterGenshinImpact/Core/Config/ScriptConfig.cs

@@ -25,4 +25,7 @@ public partial class ScriptConfig : ObservableObject
     // 已订阅的脚本路径列表
     [ObservableProperty]
     private List<string> _subscribedScriptPaths = [];
+    
+    // 选择的更新渠道URL
+    [ObservableProperty] private string _selectedRepoUrl = "";
 }