Fix incomplete functionality, nullable warnings, and async issues

Incomplete functionality fixes:
- SkiaEditor: Wire up Completed event to fire on focus lost
- X11InputMethodService: Remove unused _commitCallback field
- SkiaWebView: Set _isProperlyReparented when reparenting succeeds,
  use _lastMainX/_lastMainY to track main window position,
  add _isEmbedded guard to prevent double embedding

Nullable reference fixes:
- Easing: Reorder BounceOut before BounceIn (static init order)
- GestureManager: Use local command variable instead of re-accessing
- SkiaShell: Handle null Title with ?? operator
- GLibNative: Use null! for closure pattern
- LinuxProgramHost: Default title if null
- SkiaWebView.LoadHtml: Add null/empty check for html
- SystemThemeService: Initialize Colors with default values
- DeviceDisplayService/AppInfoService: Use var for nullable env vars
- EmailService: Add null check for message parameter

Async fixes:
- SkiaImage: Use _ = for fire-and-forget async calls
- SystemTrayService: Convert async method without await to sync Task

Reduces warnings from 156 to 133 (remaining are P/Invoke structs
and obsolete MAUI API usage)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Services/AppInfoService.cs

@@ -41,7 +41,7 @@ public class AppInfoService : IAppInfo
         {
             try
             {
-                string environmentVariable = Environment.GetEnvironmentVariable("GTK_THEME");
+                var environmentVariable = Environment.GetEnvironmentVariable("GTK_THEME");
                 if (!string.IsNullOrEmpty(environmentVariable) && environmentVariable.Contains("dark", StringComparison.OrdinalIgnoreCase))
                 {
                     return AppTheme.Dark;

Services/DeviceDisplayService.cs

@@ -73,13 +73,13 @@ public class DeviceDisplayService : IDeviceDisplay
 
     private double GetScaleFactor()
     {
-        string gdkScale = Environment.GetEnvironmentVariable("GDK_SCALE");
+        var gdkScale = Environment.GetEnvironmentVariable("GDK_SCALE");
         if (!string.IsNullOrEmpty(gdkScale) && double.TryParse(gdkScale, out var result))
         {
             return result;
         }
 
-        string qtScale = Environment.GetEnvironmentVariable("QT_SCALE_FACTOR");
+        var qtScale = Environment.GetEnvironmentVariable("QT_SCALE_FACTOR");
         if (!string.IsNullOrEmpty(qtScale) && double.TryParse(qtScale, out result))
         {
             return result;

Services/EmailService.cs

@@ -69,6 +69,7 @@ public class EmailService : IEmail
     private static string BuildMailtoUri(EmailMessage? message)
     {
         var sb = new StringBuilder("mailto:");
+        if (message == null) return sb.ToString();
 
         // Add recipients
         if (message.To?.Count > 0)

Services/SystemThemeService.cs

@@ -56,7 +56,19 @@ public class SystemThemeService
     /// <summary>
     /// System colors based on the current theme.
     /// </summary>
-    public SystemColors Colors { get; private set; }
+    public SystemColors Colors { get; private set; } = new SystemColors
+    {
+        Background = SKColors.White,
+        Surface = new SKColor(0xF5, 0xF5, 0xF5),
+        Primary = new SKColor(0x21, 0x96, 0xF3),
+        OnPrimary = SKColors.White,
+        Text = new SKColor(0x21, 0x21, 0x21),
+        TextSecondary = new SKColor(0x75, 0x75, 0x75),
+        Border = new SKColor(0xE0, 0xE0, 0xE0),
+        Divider = new SKColor(0xE0, 0xE0, 0xE0),
+        Error = new SKColor(0xF4, 0x43, 0x36),
+        Success = new SKColor(0x4C, 0xAF, 0x50)
+    };
 
     private FileSystemWatcher? _settingsWatcher;
 

Services/SystemTrayService.cs

@@ -101,7 +101,7 @@ public class SystemTrayService : IDisposable
         _ = ShowAsync();
     }
 
-    private async Task<bool> TryYadTray()
+    private Task<bool> TryYadTray()
     {
         try
         {
@@ -118,7 +118,7 @@ public class SystemTrayService : IDisposable
             };
 
             _trayProcess = Process.Start(startInfo);
-            if (_trayProcess == null) return false;
+            if (_trayProcess == null) return Task.FromResult(false);
 
             // Start reading output for menu clicks
             _ = Task.Run(async () =>
@@ -137,11 +137,11 @@ public class SystemTrayService : IDisposable
                 catch { }
             });
 
-            return true;
+            return Task.FromResult(true);
         }
         catch
         {
-            return false;
+            return Task.FromResult(false);
         }
     }
 

Services/X11InputMethodService.cs

@@ -27,7 +27,6 @@ public class X11InputMethodService : IInputMethodService, IDisposable
     private XIMProc? _preeditDoneCallback;
     private XIMProc? _preeditDrawCallback;
     private XIMProc? _preeditCaretCallback;
-    private XIMProc? _commitCallback;
 
     public bool IsActive => _isActive;
     public string PreEditText => _preEditText;