fix: 빠른 변환 진행 표시(제목 동적+%) + 영상→이미지 프레임 추출 + GPU 가속

사용자 리포트: mp4 변환 시 %안나오고 멈춤, JPEG 고정 문구, GPU 가속 부재.

- QuickProgressWindow: 제목/타이틀바를 출력 형식으로 동적화('JPEG 고정' 해결), % 텍스트 + indeterminate 표시
- FfmpegProvider: 영상→이미지(jpg/png/webp/bmp) 대표 프레임 추출 직접 엣지 (mp4→jpg가 무거운 mp4→gif→jpg 멀티홉 거치던 문제 해결)
- GPU 가속: ConvertOptions.VideoPreferGpu(기본 on) — NVENC 시도 후 실패 시 CPU 자동 폴백, 설정창 토글로 제어
- 테스트 38개 통과

src/Everything2Everything.App/App.xaml.cs

@@ -94,12 +94,13 @@ public partial class App : Application
         log.AppendLine($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff}] Quick start → {outputExtension}, {files.Count} file(s)");
         foreach (var f in files) log.AppendLine($"  src: {f}");
 
-        var progress = new QuickProgressWindow(files.Count);
+        var progress = new QuickProgressWindow(files.Count, outputExtension);
         progress.Show();
 
         try
         {
             var options = ConvertOptions.Quick();
+            options.VideoPreferGpu = Settings.Get("video.gpu") != "false";
             var reporter = new Progress<ConvertProgress>(p => progress.Report(p));
             var results = await Engine.ConvertManyAsync(files, outputExtension, options, reporter);
 

src/Everything2Everything.App/Views/MainWindow.xaml.cs

@@ -304,6 +304,8 @@ public partial class MainWindow : Wpf.Ui.Controls.FluentWindow
         var targetLang = AiTargetLangBox?.Text?.Trim();
         opts.Ai.TargetLanguage = string.IsNullOrEmpty(targetLang) ? null : targetLang;
 
+        opts.VideoPreferGpu = ((App)Application.Current).Settings.Get("video.gpu") != "false";
+
         return opts;
     }
 

src/Everything2Everything.App/Views/QuickProgressWindow.xaml

@@ -2,7 +2,7 @@
                  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                  xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"
-                 Title="JPEG로 빠른 변환"
+                 Title="빠른 변환"
                  Width="560" Height="220"
                  ExtendsContentIntoTitleBar="True"
                  WindowBackdropType="Mica"
@@ -14,7 +14,7 @@
             <RowDefinition Height="Auto"/>
             <RowDefinition Height="*"/>
         </Grid.RowDefinitions>
-        <ui:TitleBar Grid.Row="0" Title="JPEG로 빠른 변환"/>
+        <ui:TitleBar Grid.Row="0" x:Name="WindowTitleBar" Title="빠른 변환"/>
         <Grid Grid.Row="1" Margin="32,12,32,24">
             <Grid.RowDefinitions>
                 <RowDefinition Height="Auto"/>
@@ -23,7 +23,15 @@
                 <RowDefinition Height="*"/>
                 <RowDefinition Height="Auto"/>
             </Grid.RowDefinitions>
-            <TextBlock Text="변환 중…" Style="{StaticResource TextSubtitle}"/>
+            <Grid>
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="*"/>
+                    <ColumnDefinition Width="Auto"/>
+                </Grid.ColumnDefinitions>
+                <TextBlock Text="변환 중…" Style="{StaticResource TextSubtitle}"/>
+                <TextBlock x:Name="PercentText" Grid.Column="1" Text="0%"
+                           Style="{StaticResource TextSubtitle}" VerticalAlignment="Center"/>
+            </Grid>
             <TextBlock x:Name="StatusText" Grid.Row="1" Margin="0,4,0,12"
                        Style="{StaticResource TextCaption}" TextTrimming="CharacterEllipsis"/>
             <ProgressBar x:Name="OverallProgress" Grid.Row="2" Height="6"

src/Everything2Everything.App/Views/QuickProgressWindow.xaml.cs

@@ -9,10 +9,17 @@ public partial class QuickProgressWindow : FluentWindow
     private readonly int _total;
     private string? _firstSuccessOutput;
 
-    public QuickProgressWindow(int total)
+    public QuickProgressWindow(int total, string? outputExtension = null)
     {
         _total = total;
         InitializeComponent();
+
+        var label = string.IsNullOrWhiteSpace(outputExtension)
+            ? "빠른 변환"
+            : $"{outputExtension.TrimStart('.').ToUpperInvariant()}(으)로 변환";
+        Title = label;
+        WindowTitleBar.Title = label;
+
         StatusText.Text = $"0 / {_total}";
     }
 
@@ -20,7 +27,11 @@ public partial class QuickProgressWindow : FluentWindow
     {
         if (!CheckAccess()) { Dispatcher.Invoke(() => Report(p)); return; }
         var overall = _total == 0 ? 0 : (p.Index + p.FileProgress) / _total;
-        OverallProgress.Value = Math.Clamp(overall, 0, 1);
+        var clamped = Math.Clamp(overall, 0, 1);
+        OverallProgress.Value = clamped;
+        // 진행률이 멈춘 듯 보이지 않도록 % 표시 (영상 트랜스코딩처럼 오래 걸려도 단계 진행이 보이게)
+        OverallProgress.IsIndeterminate = clamped <= 0;
+        PercentText.Text = clamped <= 0 ? "처리 중…" : $"{(int)Math.Round(clamped * 100)}%";
         StatusText.Text = $"{Math.Min(p.Index + 1, _total)} / {_total} — {Path.GetFileName(p.CurrentPath)}";
     }
 
@@ -33,7 +44,9 @@ public partial class QuickProgressWindow : FluentWindow
         var failed = results.Count(r => r.Status == ConvertStatus.Failed);
         var outputs = results.Sum(r => r.OutputPaths.Count);
 
+        OverallProgress.IsIndeterminate = false;
         OverallProgress.Value = 1;
+        PercentText.Text = failed > 0 ? "완료(일부 실패)" : "100%";
         StatusText.Text = $"성공 {success}개 (출력 {outputs}), 건너뜀 {skipped}, 실패 {failed}";
         CloseButton.IsEnabled = true;
 

src/Everything2Everything.App/Views/SettingsWindow.xaml

@@ -102,7 +102,9 @@
                     <StackPanel>
                         <TextBlock Text="외부 도구" Style="{StaticResource FsBodyStyle}" FontWeight="SemiBold" FontSize="15"/>
                         <TextBlock Text="설치하면 영상/오디오·한글/Word 변환이 자동 활성화됩니다."
-                                   Style="{StaticResource FsCaptionStyle}" TextWrapping="Wrap" Margin="0,4,0,16"/>
+                                   Style="{StaticResource FsCaptionStyle}" TextWrapping="Wrap" Margin="0,4,0,12"/>
+                        <CheckBox x:Name="GpuToggle" Content="영상 변환 시 GPU 가속(NVENC) 시도 — 없으면 CPU 자동 전환"
+                                  Foreground="{StaticResource FsTextSecondary}" IsChecked="True" Margin="0,0,0,16"/>
 
                         <!-- FFmpeg -->
                         <Grid Margin="0,0,0,14">

src/Everything2Everything.App/Views/SettingsWindow.xaml.cs

@@ -35,6 +35,8 @@ public partial class SettingsWindow : Wpf.Ui.Controls.FluentWindow
 
         SetKeyStatus(OpenAiDot, OpenAiStatus, _settings.Contains("openai.apikey"), HasEnv("OPENAI_API_KEY"));
         SetKeyStatus(AnthropicDot, AnthropicStatus, _settings.Contains("anthropic.apikey"), HasEnv("ANTHROPIC_API_KEY"));
+
+        GpuToggle.IsChecked = _settings.Get("video.gpu") != "false"; // 기본 켜짐
     }
 
     private static bool HasEnv(string name) => !string.IsNullOrEmpty(Environment.GetEnvironmentVariable(name));
@@ -126,6 +128,7 @@ public partial class SettingsWindow : Wpf.Ui.Controls.FluentWindow
         if (string.IsNullOrEmpty(model)) _settings.Remove("ai.model");
         else _settings.Set("ai.model", model);
 
+        _settings.Set("video.gpu", GpuToggle.IsChecked == true ? "true" : "false");
         if (OpenAiKeyBox.Password.Length > 0) _settings.Set("openai.apikey", OpenAiKeyBox.Password);
         if (AnthropicKeyBox.Password.Length > 0) _settings.Set("anthropic.apikey", AnthropicKeyBox.Password);