Simplify splash to fade; add themed about banners

Simplify splash startup visuals by removing the multi-mode/slide behavior and always using a fade animation. Update App to create SplashWindow without a StartupVisualMode parameter and remove related fields, layout configuration, slide animation, and easing helpers from SplashWindow. Clean up unused using. Replace the single about_banner asset with theme-aware variants (about_banner_dark.png and about_banner_light.png), delete the old about_banner.png, and update AboutSettingsPage to use a DynamicResource ImageBrush (AboutBannerBrush) that selects the appropriate banner per theme.

LanMountainDesktop.Launcher/App.axaml.cs

@@ -143,8 +143,7 @@ public partial class App : Application
 
     private static SplashWindow CreateSplashWindow()
     {
-        var preferences = StartupVisualPreferencesResolver.Resolve();
-        var window = new SplashWindow(preferences.Mode);
+        var window = new SplashWindow();
         TrySetSplashVersionInfo(window, LauncherRuntimeContext.Current);
         return window;
     }

LanMountainDesktop.Launcher/Views/SplashWindow.axaml

@@ -22,37 +22,15 @@
 
   <Grid RowDefinitions="*,Auto"
         Background="#0B0B0B">
-    <Grid Grid.Row="0">
-      <Grid x:Name="CompactHero"
-            Margin="24">
-        <TextBlock x:Name="AppNameText"
-                   Text="LanMountain Desktop"
-                   FontSize="24"
-                   FontWeight="SemiBold"
-                   VerticalAlignment="Top"
-                   HorizontalAlignment="Left"
-                   Foreground="#F6F7FB" />
-      </Grid>
-
-      <Grid x:Name="FullscreenHero"
-            IsVisible="False">
-        <StackPanel HorizontalAlignment="Center"
-                    VerticalAlignment="Center"
-                    Spacing="24">
-          <Border Width="240"
-                  Height="240"
-                  Background="Transparent">
-            <Image Source="/Assets/logo_nightly.png"
-                   Stretch="Uniform" />
-          </Border>
-
-          <TextBlock Text="LanMountain Desktop"
-                     HorizontalAlignment="Center"
-                     FontSize="26"
-                     FontWeight="SemiBold"
-                     Foreground="#F6F7FB" />
-        </StackPanel>
-      </Grid>
+    <Grid Grid.Row="0"
+          Margin="24">
+      <TextBlock x:Name="AppNameText"
+                 Text="LanMountain Desktop"
+                 FontSize="24"
+                 FontWeight="SemiBold"
+                 VerticalAlignment="Top"
+                 HorizontalAlignment="Left"
+                 Foreground="#F6F7FB" />
     </Grid>
 
     <Border Grid.Row="1"

LanMountainDesktop.Launcher/Views/SplashWindow.axaml.cs

@@ -7,7 +7,6 @@ using Avalonia.Markup.Xaml;
 using Avalonia.Media;
 using Avalonia.Threading;
 using LanMountainDesktop.Launcher.Services;
-using LanMountainDesktop.Shared.Contracts.Launcher;
 
 namespace LanMountainDesktop.Launcher.Views;
 
@@ -15,25 +14,14 @@ public partial class SplashWindow : Window, ISplashStageReporter
 {
     private const int DebugModeClickThreshold = 5;
     private static readonly TimeSpan FadeAnimationDuration = TimeSpan.FromMilliseconds(160);
-    private static readonly TimeSpan SlideAnimationDuration = TimeSpan.FromMilliseconds(260);
 
-    private readonly StartupVisualMode _mode;
     private int _versionTextClickCount;
     private bool _isDebugModeOpened;
     private bool _isOpened;
-    private bool _layoutConfigured;
     private bool _dismissed;
-    private PixelPoint _targetPosition;
-    private PixelPoint _slideHiddenPosition;
 
     public SplashWindow()
-        : this(StartupVisualMode.Fade)
     {
-    }
-
-    public SplashWindow(StartupVisualMode mode)
-    {
-        _mode = mode;
         AvaloniaXamlLoader.Load(this);
         Loaded += OnWindowLoaded;
         Opened += OnWindowOpened;
@@ -55,20 +43,9 @@ public partial class SplashWindow : Window, ISplashStageReporter
         }
 
         _isOpened = true;
-        ConfigureForVisualMode();
 
-        if (_mode == StartupVisualMode.Fade)
-        {
-            Opacity = 0d;
-            await AnimateOpacityAsync(0d, 1d, FadeAnimationDuration).ConfigureAwait(false);
-            return;
-        }
-
-        Opacity = 1d;
-        if (_mode == StartupVisualMode.SlideSplash)
-        {
-            await AnimateWindowPositionAsync(_slideHiddenPosition, _targetPosition, SlideAnimationDuration, EaseOutCubic).ConfigureAwait(false);
-        }
+        Opacity = 0d;
+        await AnimateOpacityAsync(0d, 1d, FadeAnimationDuration).ConfigureAwait(false);
     }
 
     public async Task DismissAsync()
@@ -80,25 +57,13 @@ public partial class SplashWindow : Window, ISplashStageReporter
 
         _dismissed = true;
 
-        // 确保在UI线程上执行
         if (!Dispatcher.UIThread.CheckAccess())
         {
             await Dispatcher.UIThread.InvokeAsync(async () => await DismissAsync());
             return;
         }
 
-        ConfigureForVisualMode();
-
-        if (_mode == StartupVisualMode.SlideSplash)
-        {
-            var from = Position;
-            await AnimateWindowPositionAsync(from, _slideHiddenPosition, SlideAnimationDuration, EaseInCubic).ConfigureAwait(false);
-        }
-        else if (_mode == StartupVisualMode.Fade)
-        {
-            await AnimateOpacityAsync(Opacity, 0d, FadeAnimationDuration).ConfigureAwait(false);
-        }
-
+        await AnimateOpacityAsync(Opacity, 0d, FadeAnimationDuration).ConfigureAwait(false);
         Close();
     }
 
@@ -194,46 +159,6 @@ public partial class SplashWindow : Window, ISplashStageReporter
         UpdateStatus("[Debug Mode] Splash Preview");
     }
 
-    private void ConfigureForVisualMode()
-    {
-        if (_layoutConfigured)
-        {
-            return;
-        }
-
-        _layoutConfigured = true;
-        var compactHero = this.FindControl<Grid>("CompactHero");
-        var fullscreenHero = this.FindControl<Grid>("FullscreenHero");
-
-        if (_mode == StartupVisualMode.Fade)
-        {
-            compactHero?.SetCurrentValue(IsVisibleProperty, true);
-            fullscreenHero?.SetCurrentValue(IsVisibleProperty, false);
-            Background = new SolidColorBrush(Color.Parse("#0B0B0B"));
-            Width = 480;
-            Height = 320;
-            WindowStartupLocation = WindowStartupLocation.CenterScreen;
-            return;
-        }
-
-        compactHero?.SetCurrentValue(IsVisibleProperty, false);
-        fullscreenHero?.SetCurrentValue(IsVisibleProperty, true);
-        Background = Brushes.Black;
-        WindowStartupLocation = WindowStartupLocation.Manual;
-
-        var screen = Screens?.Primary ?? Screens?.All.FirstOrDefault();
-        var workingArea = screen?.WorkingArea ?? new PixelRect(0, 0, 1920, 1080);
-        var scale = Math.Max(screen?.Scaling ?? 1d, 0.01d);
-
-        Width = workingArea.Width / scale;
-        Height = workingArea.Height / scale;
-        _targetPosition = new PixelPoint(workingArea.X, workingArea.Y);
-        _slideHiddenPosition = new PixelPoint(workingArea.X + workingArea.Width, workingArea.Y);
-        Position = _mode == StartupVisualMode.SlideSplash
-            ? _slideHiddenPosition
-            : _targetPosition;
-    }
-
     private void OnVersionTextClick(object? sender, PointerPressedEventArgs e)
     {
         if (_isDebugModeOpened)
@@ -292,20 +217,6 @@ public partial class SplashWindow : Window, ISplashStageReporter
         }, duration, EaseOutCubic).ConfigureAwait(false);
     }
 
-    private async Task AnimateWindowPositionAsync(
-        PixelPoint from,
-        PixelPoint to,
-        TimeSpan duration,
-        Func<double, double> easing)
-    {
-        await AnimateAsync(progress =>
-        {
-            var currentX = (int)Math.Round(from.X + ((to.X - from.X) * progress));
-            var currentY = (int)Math.Round(from.Y + ((to.Y - from.Y) * progress));
-            Position = new PixelPoint(currentX, currentY);
-        }, duration, easing).ConfigureAwait(false);
-    }
-
     private async Task AnimateAsync(Action<double> update, TimeSpan duration, Func<double, double> easing)
     {
         if (duration <= TimeSpan.Zero)
@@ -347,6 +258,4 @@ public partial class SplashWindow : Window, ISplashStageReporter
         var inverse = 1d - value;
         return 1d - (inverse * inverse * inverse);
     }
-
-    private static double EaseInCubic(double value) => value * value * value;
 }

LanMountainDesktop/Views/SettingsPages/AboutSettingsPage.axaml

@@ -6,6 +6,19 @@
              xmlns:fi="using:FluentIcons.Avalonia.Fluent"
              x:Class="LanMountainDesktop.Views.SettingsPages.AboutSettingsPage"
              x:DataType="vm:AboutSettingsPageViewModel">
+    <UserControl.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.ThemeDictionaries>
+                <ResourceDictionary x:Key="Default">
+                    <ImageBrush x:Key="AboutBannerBrush" Source="/Assets/about_banner_light.png" Stretch="Uniform" AlignmentX="Center" AlignmentY="Center" />
+                </ResourceDictionary>
+                <ResourceDictionary x:Key="Dark">
+                    <ImageBrush x:Key="AboutBannerBrush" Source="/Assets/about_banner_dark.png" Stretch="Uniform" AlignmentX="Center" AlignmentY="Center" />
+                </ResourceDictionary>
+            </ResourceDictionary.ThemeDictionaries>
+        </ResourceDictionary>
+    </UserControl.Resources>
+
     <UserControl.Styles>
         <Style Selector="StackPanel.about-page-container">
             <Setter Property="HorizontalAlignment" Value="Stretch" />
@@ -38,10 +51,7 @@
                     Classes="about-hero-card"
                     Height="240"
                     PointerPressed="OnAboutHeroCardPointerPressed">
-                <Image Source="/Assets/about_banner.png"
-                       Stretch="Uniform"
-                       HorizontalAlignment="Center"
-                       VerticalAlignment="Center" />
+                <Panel Background="{DynamicResource AboutBannerBrush}" />
             </Border>
 
             <TextBlock Classes="settings-subsection-title"