perf: 优化 Placeholder 提示

src/MaaWpfGui/Res/Localizations/en-us.xaml

@@ -286,6 +286,7 @@ You can cancel this popup by clicking the Settings - Issue Report link. Thank yo
     <system:String x:Key="ForceGithubGlobalSource">Force using GitHub</system:String>
     <system:String x:Key="MirrorChyan">MirrorChyan</system:String>
     <system:String x:Key="MirrorChyanCdkPlaceholder">Fill after switching source</system:String>
+    <system:String x:Key="MirrorChyanCdkPlaceholder2">Please enter CDK</system:String>
     <system:String x:Key="MirrorChyanSelectedButNoCdk">Please go to ｢Settings - Update Settings｣ to configure MirrorChyan CDK or switch to Global Source.</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateTip">Resource update {0} detected. Please go to ｢Settings- Update Settings - Resource Update｣ to update manually, or fill in MirrorChayn CDK to update automatically.</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateShortTip">Resource update {0} detected</system:String>

src/MaaWpfGui/Res/Localizations/ja-jp.xaml

@@ -287,6 +287,7 @@
     <system:String x:Key="ForceGithubGlobalSource">GitHub を強制使用</system:String>
     <system:String x:Key="MirrorChyan">MirrorChyan</system:String>
     <system:String x:Key="MirrorChyanCdkPlaceholder">更新ソース切替後入力</system:String>
+    <system:String x:Key="MirrorChyanCdkPlaceholder2">CDKを入力してください</system:String>
     <system:String x:Key="MirrorChyanSelectedButNoCdk">｢設定 - 更新設定｣ に移動して MirrorChyan CDK を設定するか、グローバル ソースに切り替えてください。</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateTip">リソース更新 {0} が検出されました。｢設定 - 更新設定 - リソース更新｣ に移動して手動で更新するか、MirrorChayn CDK を入力して自動的に更新してください。</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateShortTip">リソース更新 {0} が検出されました</system:String>

src/MaaWpfGui/Res/Localizations/ko-kr.xaml

@@ -286,6 +286,7 @@
     <system:String x:Key="ForceGithubGlobalSource">GitHub 강제 사용</system:String>
     <system:String x:Key="MirrorChyan">MirrorChyan</system:String>
     <system:String x:Key="MirrorChyanCdkPlaceholder">소스 전환 후 입력</system:String>
+    <system:String x:Key="MirrorChyanCdkPlaceholder2">CDK를 입력해 주세요</system:String>
     <system:String x:Key="MirrorChyanSelectedButNoCdk">｢설정 - 업데이트 설정｣ 으로 이동하여 MirrorChyan CDK를 구성하거나 글로벌 소스로 전환하세요.</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateTip">리소스 업데이트 {0}이 감지되었습니다. ｢설정 - 업데이트 설정 - 리소스 업데이트｣ 로 이동하여 수동으로 업데이트하거나, MirrorChyan CDK를 입력하여 자동으로 업데이트하세요.</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateShortTip">리소스 업데이트 {0}이 감지되었습니다</system:String>

src/MaaWpfGui/Res/Localizations/zh-cn.xaml

@@ -287,6 +287,7 @@
     <system:String x:Key="ForceGithubGlobalSource">强制使用 GitHub</system:String>
     <system:String x:Key="MirrorChyan">Mirror酱</system:String>
     <system:String x:Key="MirrorChyanCdkPlaceholder">切换更新源后填写</system:String>
+    <system:String x:Key="MirrorChyanCdkPlaceholder2">请输入 CDK</system:String>
     <system:String x:Key="MirrorChyanSelectedButNoCdk">请前往 ｢设置-更新设置｣ 配置 Mirror酱 CDK 或切换海外源。</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateTip">检测到资源更新: {0}。请前往 ｢设置-更新设置-资源更新｣ 手动更新，或配置 Mirror酱 CDK 以自动更新。</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateShortTip">检测到资源更新: {0}</system:String>

src/MaaWpfGui/Res/Localizations/zh-tw.xaml

@@ -286,6 +286,7 @@
     <system:String x:Key="ForceGithubGlobalSource">強制使用 GitHub</system:String>
     <system:String x:Key="MirrorChyan">MirrorChyan</system:String>
     <system:String x:Key="MirrorChyanCdkPlaceholder">切換更新源後填寫</system:String>
+    <system:String x:Key="MirrorChyanCdkPlaceholder2">請輸入 CDK</system:String>
     <system:String x:Key="MirrorChyanSelectedButNoCdk">請前往 ｢設定-更新設定｣ 設定 MirrorChyan CDK 或切換到全域來源。</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateTip">偵測到資源更新: {0}。請前往 ｢設定-更新設定-資源更新｣ 手動更新，或設定 MirrorChayn CDK 以自動更新。</system:String>
     <system:String x:Key="MirrorChyanResourceUpdateShortTip">偵測到資源更新: {0}</system:String>

src/MaaWpfGui/ViewModels/UserControl/Settings/VersionUpdateSettingsUserControlModel.cs

@@ -272,6 +272,7 @@ public class VersionUpdateSettingsUserControlModel : PropertyChangedBase
         {
             SetAndNotify(ref _updateSource, value);
             ConfigurationHelper.SetGlobalValue(ConfigurationKeys.UpdateSource, value);
+            NotifyOfPropertyChange(nameof(MirrorChyanCdkPlaceholder));
         }
     }
 
@@ -313,6 +314,11 @@ public class VersionUpdateSettingsUserControlModel : PropertyChangedBase
         }
     }
 
+    public string MirrorChyanCdkPlaceholder =>
+        UpdateSource != "MirrorChyan"
+            ? LocalizationHelper.GetString("MirrorChyanCdkPlaceholder")
+            : LocalizationHelper.GetString("MirrorChyanCdkPlaceholder2");
+
     private bool _startupUpdateCheck = Convert.ToBoolean(ConfigurationHelper.GetGlobalValue(ConfigurationKeys.StartupUpdateCheck, bool.TrueString));
 
     /// <summary>

src/MaaWpfGui/Views/UserControl/Settings/VersionUpdateSettingsUserControl.xaml

@@ -137,7 +137,7 @@
                                 Width="150"
                                 HorizontalAlignment="Left"
                                 VerticalAlignment="Center"
-                                hc:InfoElement.Placeholder="{DynamicResource MirrorChyanCdkPlaceholder}"
+                                hc:InfoElement.Placeholder="{Binding MirrorChyanCdkPlaceholder}"
                                 IsEnabled="{c:Binding 'UpdateSource == "MirrorChyan"'}"
                                 IsSafeEnabled="False"
                                 ShowEyeButton="True"