Klausurauswertung (1.5) — Kapitel 1 damit vollständig

Neuer Dialog ExamEvaluationDialog, erreichbar über "Auswertung" im
Klausuren-Tab (Button + Kontextmenü bei ausgewählter Klausur):

- Notenspiegel als Balkendiagramm, Durchschnitt (via bestehendes
  GradingService.WeightedAverage), Median, sowie ein Schwellenwert-
  Anteil ("< 5/4 Punkte" bei Punktesystem, "nicht ausreichend 5/6"
  bei Notensystem 1–6).
- Aufgabenanalyse: durchschnittlicher Erfüllungsgrad je Aufgabe,
  auffällig schwache (Ø < 50 %) rot markiert.
- Notenschlüssel verschieben: gleicher Editor wie im Klausur-Dialog,
  Änderungen wirken sich sofort im Notenspiegel aus; erst
  "Übernehmen" schreibt sie in die Klausur zurück.
- CSV-Export direkt im Dialog, analog zum bestehenden JSON-Export der
  Kompetenzkataloge — ohne die noch fehlende Export-Infrastruktur aus
  Kapitel 11 vorwegzunehmen.
- Abwesende werden konsequent aus allen Statistiken ausgeschlossen
  (löst den in 1.4.3 offen gelassenen Punkt ein).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

LehrerApp.Desktop/Views/Groups/ExamEvaluationDialog.axaml

@@ -0,0 +1,149 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels.Groups"
+        x:Class="LehrerApp.Desktop.Views.Groups.ExamEvaluationDialog"
+        x:DataType="vm:ExamEvaluationDialogViewModel"
+        Title="{Binding ExamTitle}"
+        Width="760" Height="820" MinWidth="600" MinHeight="480"
+        CanResize="True" WindowStartupLocation="CenterOwner">
+
+  <Grid RowDefinitions="*,Auto" Margin="24">
+    <ScrollViewer Grid.Row="0">
+      <StackPanel Spacing="16" Margin="0,0,12,0">
+
+        <StackPanel Spacing="2">
+          <TextBlock Text="{Binding ExamTitle}" FontSize="18" FontWeight="SemiBold"/>
+          <TextBlock Text="{Binding ExamDateLabel}" FontSize="12" Opacity="0.6"/>
+        </StackPanel>
+
+        <!-- Kennzahlen -->
+        <UniformGrid Columns="3" Rows="2">
+          <StackPanel Margin="0,0,12,10">
+            <TextBlock Text="DURCHSCHNITT" FontSize="10" FontWeight="Bold" Opacity="0.5"/>
+            <TextBlock Text="{Binding AverageDisplay}" FontSize="20" FontWeight="SemiBold"/>
+          </StackPanel>
+          <StackPanel Margin="0,0,12,10">
+            <TextBlock Text="MEDIAN" FontSize="10" FontWeight="Bold" Opacity="0.5"/>
+            <TextBlock Text="{Binding MedianDisplay}" FontSize="20" FontWeight="SemiBold"/>
+          </StackPanel>
+          <StackPanel Margin="0,0,12,10">
+            <TextBlock Text="BEWERTET / ABWESEND" FontSize="10" FontWeight="Bold" Opacity="0.5"/>
+            <TextBlock FontSize="20" FontWeight="SemiBold">
+              <Run Text="{Binding GradedCount}"/>
+              <Run Text=" / "/>
+              <Run Text="{Binding AbsentCount}"/>
+            </TextBlock>
+          </StackPanel>
+          <StackPanel Margin="0,0,12,0" IsVisible="{Binding BelowThresholdLabel1, Converter={x:Static StringConverters.IsNotNullOrEmpty}}">
+            <TextBlock Text="{Binding BelowThresholdLabel1}" FontSize="10" FontWeight="Bold" Opacity="0.5"
+                       TextWrapping="Wrap"/>
+            <TextBlock Text="{Binding BelowThresholdDisplay1}" FontSize="20" FontWeight="SemiBold"/>
+          </StackPanel>
+          <StackPanel Margin="0,0,12,0" IsVisible="{Binding BelowThresholdLabel2, Converter={x:Static StringConverters.IsNotNullOrEmpty}}">
+            <TextBlock Text="{Binding BelowThresholdLabel2}" FontSize="10" FontWeight="Bold" Opacity="0.5"
+                       TextWrapping="Wrap"/>
+            <TextBlock Text="{Binding BelowThresholdDisplay2}" FontSize="20" FontWeight="SemiBold"/>
+          </StackPanel>
+        </UniformGrid>
+
+        <Separator/>
+
+        <!-- Notenspiegel -->
+        <TextBlock Text="Notenspiegel" FontSize="14" FontWeight="SemiBold"/>
+        <ItemsControl ItemsSource="{Binding GradeDistribution}">
+          <ItemsControl.ItemTemplate>
+            <DataTemplate x:DataType="vm:GradeBarItem">
+              <Grid ColumnDefinitions="40,210,*" Margin="0,3">
+                <TextBlock Grid.Column="0" Text="{Binding Grade}" VerticalAlignment="Center" FontWeight="SemiBold"/>
+                <Border Grid.Column="1" HorizontalAlignment="Left" Height="16" CornerRadius="3"
+                        Width="{Binding BarWidth}"
+                        Background="{DynamicResource SystemControlBackgroundAccentBrush}"/>
+                <TextBlock Grid.Column="2" Text="{Binding CountDisplay}" FontSize="12" Opacity="0.7"
+                           VerticalAlignment="Center" Margin="8,0,0,0"/>
+              </Grid>
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+        <TextBlock Text="Noch keine bewerteten Ergebnisse." Opacity="0.4" FontSize="13"
+                   IsVisible="{Binding !GradedCount}"/>
+
+        <Separator/>
+
+        <!-- Aufgabenanalyse -->
+        <TextBlock Text="Aufgabenanalyse" FontSize="14" FontWeight="SemiBold"/>
+        <ItemsControl ItemsSource="{Binding TaskAnalysis}">
+          <ItemsControl.Styles>
+            <Style Selector="Border.taskbar">
+              <Setter Property="Background" Value="{DynamicResource SystemControlBackgroundAccentBrush}"/>
+            </Style>
+            <Style Selector="Border.taskbar.weak">
+              <Setter Property="Background" Value="#E53935"/>
+            </Style>
+            <Style Selector="TextBlock.tasklabel">
+              <Setter Property="Foreground" Value="{DynamicResource SystemControlForegroundBaseHighBrush}"/>
+            </Style>
+            <Style Selector="TextBlock.tasklabel.weak">
+              <Setter Property="Foreground" Value="#E53935"/>
+              <Setter Property="FontWeight" Value="SemiBold"/>
+            </Style>
+          </ItemsControl.Styles>
+          <ItemsControl.ItemTemplate>
+            <DataTemplate x:DataType="vm:TaskAnalysisItem">
+              <Grid ColumnDefinitions="180,210,*" Margin="0,3">
+                <TextBlock Grid.Column="0" Classes="tasklabel" Classes.weak="{Binding IsWeak}"
+                           Text="{Binding Label}" VerticalAlignment="Center" TextTrimming="CharacterEllipsis"/>
+                <Border Grid.Column="1" Classes="taskbar" Classes.weak="{Binding IsWeak}"
+                        HorizontalAlignment="Left" Height="16" CornerRadius="3" Width="{Binding BarWidth}"/>
+                <TextBlock Grid.Column="2" Text="{Binding AvgPercentDisplay}" FontSize="12" Opacity="0.7"
+                           VerticalAlignment="Center" Margin="8,0,0,0"/>
+              </Grid>
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+        <TextBlock Text="Auffällig schwache Aufgaben (Ø unter 50 %) sind rot markiert." Opacity="0.4" FontSize="11"
+                   IsVisible="{Binding TaskAnalysis.Count}"/>
+
+        <Separator/>
+
+        <!-- Notenschlüssel verschieben -->
+        <Grid ColumnDefinitions="*,Auto">
+          <TextBlock Grid.Column="0" Text="Notenschlüssel verschieben" FontSize="14" FontWeight="SemiBold" VerticalAlignment="Center"/>
+          <Button Grid.Column="1" Content="＋ Stufe" Command="{Binding AddGradingKeyRowCommand}"/>
+        </Grid>
+        <TextBlock Text="Änderungen wirken sich sofort auf den Notenspiegel oben aus. Erst mit &quot;Übernehmen&quot; werden sie an der Klausur gespeichert."
+                   FontSize="11" Opacity="0.5" TextWrapping="Wrap"/>
+
+        <ItemsControl ItemsSource="{Binding GradingKeyEntries}">
+          <ItemsControl.ItemTemplate>
+            <DataTemplate x:DataType="vm:GradingKeyEntryEditItem">
+              <Grid ColumnDefinitions="90,90,*,Auto" Margin="0,0,0,4">
+                <TextBox Grid.Column="0" Text="{Binding Grade}" PlaceholderText="Note" Margin="0,0,6,0"/>
+                <NumericUpDown Grid.Column="1" Value="{Binding MinPercent}" Minimum="0" Maximum="100"
+                               FormatString="0.##" Width="90" ShowButtonSpinner="False" Margin="0,0,6,0"/>
+                <TextBlock Grid.Column="2" Text="{Binding AbsolutePointsDisplay}" FontSize="12" Opacity="0.65"
+                           VerticalAlignment="Center"/>
+                <Button Grid.Column="3" Content="✕" Command="{Binding RemoveCommand}" Padding="6,2"/>
+              </Grid>
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+
+        <TextBlock Text="{Binding GradingKeyValidation}" Foreground="Red" FontSize="12"
+                   IsVisible="{Binding GradingKeyValidation, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+
+        <Grid ColumnDefinitions="*,Auto">
+          <TextBlock Grid.Column="0" Text="{Binding GradingKeyStatus}" Foreground="Green" FontSize="12"
+                     VerticalAlignment="Center"
+                     IsVisible="{Binding GradingKeyStatus, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+          <Button Grid.Column="1" Content="Übernehmen" Command="{Binding ApplyGradingKeyCommand}"/>
+        </Grid>
+
+      </StackPanel>
+    </ScrollViewer>
+
+    <Grid Grid.Row="1" ColumnDefinitions="Auto,*,Auto" Margin="0,16,0,0">
+      <Button Grid.Column="0" Content="Als CSV exportieren" Click="OnExportClick"/>
+      <Button Grid.Column="2" Content="Fertig" Click="OnClose"/>
+    </Grid>
+  </Grid>
+</Window>

LehrerApp.Desktop/Views/Groups/ExamEvaluationDialog.axaml.cs

@@ -0,0 +1,30 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Platform.Storage;
+using LehrerApp.Desktop.ViewModels.Groups;
+
+namespace LehrerApp.Desktop.Views.Groups;
+
+public partial class ExamEvaluationDialog : Window
+{
+    public ExamEvaluationDialog() => InitializeComponent();
+
+    private async void OnExportClick(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is not ExamEvaluationDialogViewModel vm) return;
+        var topLevel = TopLevel.GetTopLevel(this);
+        if (topLevel is null) return;
+
+        var file = await topLevel.StorageProvider.SaveFilePickerAsync(new FilePickerSaveOptions
+        {
+            Title             = "Klausurauswertung exportieren",
+            SuggestedFileName = $"Auswertung_{vm.ExamTitle}.csv",
+            FileTypeChoices   = [new FilePickerFileType("CSV-Dateien") { Patterns = ["*.csv"] }],
+        });
+
+        if (file is null) return;
+        await File.WriteAllTextAsync(file.Path.LocalPath, vm.ExportCsv());
+    }
+
+    private void OnClose(object? sender, RoutedEventArgs e) => Close();
+}

LehrerApp.Desktop/Views/Groups/GroupDetailView.axaml

@@ -71,6 +71,7 @@
           <StackPanel Grid.Row="0" Orientation="Horizontal" Spacing="8" Margin="0,0,0,8"
                       IsVisible="{Binding SelectedExam, Converter={x:Static ObjectConverters.IsNotNull}}">
             <Button Content="Punkte eingeben" Command="{Binding GradeExamCommand}"/>
+            <Button Content="Auswertung"    Command="{Binding EvaluateExamCommand}"/>
             <Button Content="Bearbeiten"    Command="{Binding EditExamCommand}"/>
             <Button Content="Duplizieren"   Command="{Binding DuplicateExamCommand}"/>
             <SplitButton Content="Status ▸" Command="{Binding AdvanceExamStatusCommand}">
@@ -113,6 +114,7 @@
             <DataGrid.ContextMenu>
               <ContextMenu>
                 <MenuItem Header="Punkte eingeben" Command="{Binding GradeExamCommand}"/>
+                <MenuItem Header="Auswertung"    Command="{Binding EvaluateExamCommand}"/>
                 <MenuItem Header="Bearbeiten"    Command="{Binding EditExamCommand}"/>
                 <MenuItem Header="Duplizieren"   Command="{Binding DuplicateExamCommand}"/>
                 <MenuItem Header="Status">

LehrerApp.Desktop/Views/Groups/GroupDetailView.axaml.cs

@@ -22,6 +22,7 @@ public partial class GroupDetailView : UserControl
             vm.OnDuplicateExam   = ShowDuplicateExamDialog;
             vm.OnConfirmDeleteExam = ShowDeleteExamDialog;
             vm.OnGradeExam       = ShowGradeExamDialog;
+            vm.OnEvaluateExam    = ShowEvaluateExamDialog;
         }
     }
 
@@ -92,4 +93,19 @@ public partial class GroupDetailView : UserControl
         var owner = TopLevel.GetTopLevel(this) as Window;
         if (owner is not null) await dialog.ShowDialog(owner);
     }
+
+    private async Task ShowEvaluateExamDialog(Exam exam)
+    {
+        if (DataContext is not GroupDetailViewModel vm || vm.Group is null) return;
+
+        var dialogVm = new ExamEvaluationDialogViewModel(
+            App.Services.GetRequiredService<IExamRepository>(),
+            App.Services.GetRequiredService<IExamResultRepository>(),
+            App.Services.GetRequiredService<GradingService>(),
+            exam, vm.Group.GradingSystem);
+
+        var dialog = new ExamEvaluationDialog { DataContext = dialogVm };
+        var owner = TopLevel.GetTopLevel(this) as Window;
+        if (owner is not null) await dialog.ShowDialog(owner);
+    }
 }