Add overall progress, notifications, and UI polish

- Unify audio/subtitle selection: single-select, auto-default,
  cross-file propagation by exact name
- Show file size in queue, group divider and reordered columns in
  track table, drop accent highlight on row selection
- Add cumulative progress bar (files finished, MB copied) to the
  stripping window
- Add Windows toast notifications on stripping completion/cancel/error
- Restart the app after settings are changed; Cancel no longer
  clears the queue, only closes the window
- Add ConfigureAwait(false) throughout MkvService so concurrent
  strips don't starve the UI thread
- Hardcode scan/strip concurrency (10/5) instead of exposing it in
  Settings

Services/MkvService.cs

@@ -74,8 +74,8 @@ public class MkvService
         // fill up and deadlock the child process indefinitely.
         var stdoutTask = process.StandardOutput.ReadToEndAsync(ct);
         var stderrTask = process.StandardError.ReadToEndAsync(ct);
-        await Task.WhenAll(stdoutTask, stderrTask);
-        await process.WaitForExitAsync(ct);
+        await Task.WhenAll(stdoutTask, stderrTask).ConfigureAwait(false);
+        await process.WaitForExitAsync(ct).ConfigureAwait(false);
 
         string stdout = stdoutTask.Result;
         string stderr = stderrTask.Result;
@@ -151,9 +151,15 @@ public class MkvService
             });
         }
 
+        for (int i = 0; i < items.Count; i++)
+        {
+            items[i].IsGroupStart = i > 0 && items[i].Type != items[i - 1].Type;
+        }
+
         return items;
     }
 
+
     /// <summary>
     /// Scans a single file and determines which audio/subtitle track IDs
     /// should be kept. Fails if only English audio is present, or if the
@@ -164,7 +170,7 @@ public class MkvService
         var scan = new ScanResult { FilePath = filePath };
         try
         {
-            var info = await IdentifyAsync(filePath, ct);
+            var info = await IdentifyAsync(filePath, ct).ConfigureAwait(false);
 
             var audioTracks = info.Tracks.Where(t => t.Type == "audio").ToList();
             var subtitleTracks = info.Tracks.Where(t => t.Type == "subtitles").ToList();
@@ -325,9 +331,9 @@ public class MkvService
             {
                 byte[] buffer = new byte[1024 * 1024];
                 int read;
-                while ((read = await source.ReadAsync(buffer, ct)) > 0)
+                while ((read = await source.ReadAsync(buffer, ct).ConfigureAwait(false)) > 0)
                 {
-                    await dest.WriteAsync(buffer.AsMemory(0, read), ct);
+                    await dest.WriteAsync(buffer.AsMemory(0, read), ct).ConfigureAwait(false);
                     copied += read;
 
                     var elapsed = stopwatch.Elapsed;
@@ -450,11 +456,11 @@ public class MkvService
             using var throughputCts = new CancellationTokenSource();
             var throughputTask = MonitorThroughputAsync(tempFile, fileName, percentState, progress, throughputCts.Token);
 
-            await process.WaitForExitAsync(CancellationToken.None);
+            await process.WaitForExitAsync(CancellationToken.None).ConfigureAwait(false);
             throughputCts.Cancel();
-            string stdout = await stdoutTask;
-            string stderr = await stderrTask;
-            try { await throughputTask; } catch (OperationCanceledException) { }
+            string stdout = await stdoutTask.ConfigureAwait(false);
+            string stderr = await stderrTask.ConfigureAwait(false);
+            try { await throughputTask.ConfigureAwait(false); } catch (OperationCanceledException) { }
 
             if (wasKilled)
             {
@@ -543,7 +549,7 @@ public class MkvService
     {
         var fullOutput = new System.Text.StringBuilder();
         string? line;
-        while ((line = await process.StandardOutput.ReadLineAsync()) != null)
+        while ((line = await process.StandardOutput.ReadLineAsync().ConfigureAwait(false)) != null)
         {
             fullOutput.AppendLine(line);
             var match = ProgressRegex.Match(line);
@@ -565,7 +571,7 @@ public class MkvService
         {
             while (true)
             {
-                await Task.Delay(sampleInterval, stopToken);
+                await Task.Delay(sampleInterval, stopToken).ConfigureAwait(false);
 
                 long currentBytes = 0;
                 try { currentBytes = new FileInfo(tempFile).Length; } catch { }

Services/NotificationService.cs

@@ -0,0 +1,48 @@
+using System.Drawing;
+using System.Windows.Forms;
+
+namespace Futonizer.Services;
+
+/// <summary>
+/// Fires native Windows notifications (via a transient tray icon's balloon
+/// tip) to let the user know processing has finished, even if the app
+/// window isn't focused.
+/// </summary>
+public static class NotificationService
+{
+    public static void ShowToast(string title, string message)
+    {
+        try
+        {
+            Icon icon;
+            try
+            {
+                icon = System.Drawing.Icon.ExtractAssociatedIcon(Environment.ProcessPath!) ?? SystemIcons.Application;
+            }
+            catch
+            {
+                icon = SystemIcons.Application;
+            }
+
+            var notifyIcon = new NotifyIcon
+            {
+                Icon = icon,
+                Visible = true,
+                BalloonTipTitle = title,
+                BalloonTipText = message,
+                BalloonTipIcon = ToolTipIcon.Info,
+            };
+
+            notifyIcon.BalloonTipClosed += (_, _) => notifyIcon.Dispose();
+            notifyIcon.BalloonTipClicked += (_, _) => notifyIcon.Dispose();
+            notifyIcon.ShowBalloonTip(5000);
+
+            // Fallback in case neither event fires (e.g. notifications disabled).
+            _ = Task.Delay(10000).ContinueWith(_ => notifyIcon.Dispose());
+        }
+        catch
+        {
+            // Notifications are best-effort; never let a failure here affect the app.
+        }
+    }
+}