Add startup visual modes and attempt registry

Implement startup visual behavior, de-duplicate startup attempts, and improve failure UX.

Key changes:
- Add spec and docs for startup visuals and timing contract (.trae/specs and docs/LAUNCHER_STARTUP_VISUALS.md).
- Introduce StartupVisualPreferences contract and resolver; create SplashWindow via resolved mode.
- Add StartupAttemptRecord model and a file-backed StartupAttemptRegistry to persist and coordinate in-progress startup attempts (attach/adopt, soft/hard timeouts, IPC/connect state, lifecycle updates).
- Update LauncherFlowCoordinator to: adopt/attach to existing attempts, track IPC connection and soft/hard timeouts (30s/120s), show delayed UI state, attempt foreground recovery via public IPC, compose detailed launch result metadata, and mark registry states (soft timeout, detached waiting, succeeded, failed).
- Add TryActivateExistingInstanceAsync to attempt activating an existing desktop via IPC.
- Change failure flow: ShowFailureWindowAsync now returns user choice; ErrorWindow updated to present Activate/Wait/Open Logs/Exit semantics and new layouts/styles; improved button wiring and debug/dev mode handling.
- Add UI and resource tweaks (ErrorWindow and SplashWindow changes), project asset link for nightly logo, and unit tests for StartupVisualPreferences.

These changes prevent duplicate desktop processes during slow startups, provide clearer UX for delayed startups, and persist startup attempt state across Launcher invocations for safer recovery/attach behavior.

LanMountainDesktop.Launcher/Views/ErrorWindow.axaml

@@ -3,102 +3,96 @@
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         xmlns:views="clr-namespace:LanMountainDesktop.Launcher.Views"
-        xmlns:ui="using:FluentAvalonia.UI.Controls"
         mc:Ignorable="d"
-        d:DesignWidth="520"
-        d:DesignHeight="280"
         x:Class="LanMountainDesktop.Launcher.Views.ErrorWindow"
         x:DataType="views:ErrorWindow"
-        Title="阑山桌面"
-        Width="520"
-        Height="280"
+        Title="LanMountain Desktop"
+        Width="560"
+        Height="320"
         CanResize="False"
         WindowStartupLocation="CenterScreen"
-        Background="{DynamicResource SolidBackgroundFillColorBaseBrush}"
+        Background="#111318"
         TransparencyLevelHint="None"
         Icon="/Assets/logo.ico">
   <Design.DataContext>
     <views:ErrorWindow />
   </Design.DataContext>
 
-  <!-- Fluent Design 风格对话框布局 -->
   <Grid RowDefinitions="*,Auto">
-    <!-- 主内容区域：左侧图标 + 右侧文字 -->
-    <Grid Grid.Row="0" Margin="24,24,24,16" ColumnDefinitions="Auto,*">
-      
-      <!-- 左侧：错误图标（可点击进入调试模式） -->
+    <Grid Grid.Row="0"
+          Margin="24"
+          ColumnDefinitions="Auto,*">
       <Border x:Name="ErrorIconBorder"
               Grid.Column="0"
-              Width="48"
-              Height="48"
-              Margin="0,4,16,0"
-              Background="{DynamicResource SystemFillColorCriticalBackgroundBrush}"
-              CornerRadius="24"
+              Width="52"
+              Height="52"
+              Margin="0,4,18,0"
+              Background="#2B161A"
+              CornerRadius="26"
               VerticalAlignment="Top">
-        <TextBlock Text="&#xEA39;"
+        <TextBlock Text="!"
                    FontSize="24"
-                   FontFamily="{DynamicResource SymbolThemeFontFamily}"
-                   Foreground="{DynamicResource SystemFillColorCriticalBrush}"
+                   FontWeight="Bold"
+                   Foreground="#FFB4AB"
                    HorizontalAlignment="Center"
-                   VerticalAlignment="Center"/>
+                   VerticalAlignment="Center" />
       </Border>
-      
-      <!-- 右侧：标题 + 内容 -->
-      <StackPanel Grid.Column="1" Spacing="8">
-        <!-- 标题 -->
+
+      <StackPanel Grid.Column="1"
+                  Spacing="10">
         <TextBlock x:Name="TitleText"
-                   Text="启动失败"
-                   FontSize="18"
+                   Text="Launcher could not confirm startup"
+                   FontSize="20"
                    FontWeight="SemiBold"
-                   Foreground="{DynamicResource TextFillColorPrimaryBrush}"
-                   TextWrapping="Wrap"/>
-        
-        <!-- 错误信息 -->
+                   Foreground="#F6F7FB"
+                   TextWrapping="Wrap" />
+
         <TextBlock x:Name="ErrorMessageText"
-                   Text="找不到阑山桌面应用程序。"
+                   Text="LanMountain Desktop did not reach the expected startup state."
                    FontSize="14"
-                   Foreground="{DynamicResource TextFillColorSecondaryBrush}"
+                   Foreground="#D2D7E1"
                    TextWrapping="Wrap"
-                   LineHeight="20"/>
-        
-        <!-- 建议信息 -->
+                   LineHeight="22" />
+
         <TextBlock x:Name="SuggestionText"
-                   Text="请确保应用程序已正确安装，或尝试重新安装。"
+                   Text="You can inspect logs, retry when the old process is gone, or reactivate the current instance."
                    FontSize="13"
-                   Foreground="{DynamicResource TextFillColorTertiaryBrush}"
+                   Foreground="#9BA5B7"
                    TextWrapping="Wrap"
-                   LineHeight="18"
-                   Margin="0,4,0,0"/>
+                   LineHeight="20" />
       </StackPanel>
     </Grid>
 
-    <!-- 底部：按钮区域 -->
     <Border Grid.Row="1"
-            Background="{DynamicResource CardBackgroundFillColorDefaultBrush}"
-            Padding="24,16">
-      <Grid ColumnDefinitions="*,Auto">
+            Padding="24,16"
+            Background="#171A21">
+      <Grid ColumnDefinitions="*,Auto,Auto,Auto"
+            ColumnSpacing="8">
         <Button x:Name="OpenLogButton"
                 Grid.Column="0"
-                Content="打开日志"
-                Width="100"
-                Height="32"
-                FontSize="13"
-                HorizontalAlignment="Left"/>
-        <StackPanel Grid.Column="1"
-                    Orientation="Horizontal" 
-                    Spacing="8">
-          <Button x:Name="ExitButton"
-                  Content="退出"
-                  Width="80"
-                  Height="32"
-                  FontSize="13"/>
-          <Button x:Name="RetryButton"
-                  Content="重试"
-                  Width="80"
-                  Height="32"
-                  FontSize="13"
-                  Theme="{DynamicResource AccentButtonTheme}"/>
-        </StackPanel>
+                Content="Open Logs"
+                MinWidth="108"
+                Height="34"
+                HorizontalAlignment="Left" />
+
+        <Button x:Name="SecondaryActionButton"
+                Grid.Column="1"
+                Content="Wait"
+                MinWidth="108"
+                Height="34"
+                IsVisible="False" />
+
+        <Button x:Name="ExitButton"
+                Grid.Column="2"
+                Content="Exit"
+                MinWidth="90"
+                Height="34" />
+
+        <Button x:Name="PrimaryActionButton"
+                Grid.Column="3"
+                Content="Retry"
+                MinWidth="108"
+                Height="34" />
       </Grid>
     </Border>
   </Grid>