Refactor data location paths and add background service

Refactor DataLocationResolver to centralize data path resolution (ResolveLauncherDataPath, ResolveDesktopDataPath, ResolveConfigPath, ResolveLauncherLogsPath, ResolveLauncherStatePath) and replace usages of the previous ".launcher" layout with a "Launcher" folder. Update API: LoadConfig/SaveConfig reorganized and ApplyLocationChoice now accepts an optional custom path and migration flag; migration logic updated accordingly. Update dependent services and views (Logger, DeploymentLocator, UpdateEngineService, OobeStateService, StartupAttemptRegistry, LauncherDebugSettingsStore, OobeWindow) to use the new resolver APIs and paths. Add LauncherBackgroundService to load/validate/cache a custom splash background image and wire it into SplashWindow (AXAML/Axaml.cs) with UI placeholders and overlay. Misc: minor cleanup of Oobe/Splash XAML and related code adjustments and logging improvements.

LanMountainDesktop.Launcher/Views/OobeWindow.axaml

@@ -23,7 +23,6 @@
   </Design.DataContext>
 
   <Grid x:Name="ContentGrid">
-
     <!-- 步骤 1: 打字机动画开场 -->
     <Grid x:Name="TypingStep" Margin="60,80,60,60">
       <!-- 主标题区域（左上角） -->

LanMountainDesktop.Launcher/Views/OobeWindow.axaml.cs

@@ -431,7 +431,7 @@ public partial class OobeWindow : Window
         // 应用数据位置选择
         if (!_isDebugMode)
         {
-            _resolver.ApplyLocationChoice(_selectedDataLocationMode, _migrateExistingData);
+            _resolver.ApplyLocationChoice(_selectedDataLocationMode, null, _migrateExistingData);
         }
 
         await NavigateToStep(4);

LanMountainDesktop.Launcher/Views/SplashWindow.axaml

@@ -20,8 +20,20 @@
     <views:SplashWindow />
   </Design.DataContext>
 
-  <Grid RowDefinitions="*,Auto"
-        Background="#0B0B0B">
+  <Grid RowDefinitions="*,Auto">
+    <!-- 背景图片 -->
+    <Image x:Name="BackgroundImage"
+           Grid.RowSpan="2"
+           Stretch="UniformToFill"
+           IsVisible="False"
+           Opacity="0"/>
+
+    <!-- 半透明遮罩层 -->
+    <Border x:Name="BackgroundOverlay"
+            Grid.RowSpan="2"
+            Background="#0B0B0B"
+            Opacity="0.85"/>
+
     <Grid Grid.Row="0"
           Margin="24">
       <TextBlock x:Name="AppNameText"

LanMountainDesktop.Launcher/Views/SplashWindow.axaml.cs

@@ -29,12 +29,40 @@ public partial class SplashWindow : Window, ISplashStageReporter
 
     private void OnWindowLoaded(object? sender, RoutedEventArgs e)
     {
+        InitializeBackgroundImage();
+
         if (this.FindControl<Border>("VersionTextBorder") is { } versionBorder)
         {
             versionBorder.PointerPressed += OnVersionTextClick;
         }
     }
 
+    private void InitializeBackgroundImage()
+    {
+        try
+        {
+            var imageInfo = LauncherBackgroundService.LoadBackgroundImage();
+            if (imageInfo is { IsValid: true, Bitmap: not null })
+            {
+                if (this.FindControl<Image>("BackgroundImage") is { } backgroundImage)
+                {
+                    backgroundImage.Source = imageInfo.Bitmap;
+                    backgroundImage.IsVisible = true;
+                    backgroundImage.Opacity = 1;
+                }
+                Logger.Info("[SplashWindow] 背景图片加载成功");
+            }
+            else if (imageInfo is { Exists: true, IsValid: false })
+            {
+                Logger.Warn($"[SplashWindow] 背景图片校验失败: {imageInfo.ErrorMessage}");
+            }
+        }
+        catch (Exception ex)
+        {
+            Logger.Warn($"[SplashWindow] 加载背景图片失败: {ex.Message}");
+        }
+    }
+
     private async void OnWindowOpened(object? sender, EventArgs e)
     {
         if (_isOpened)