feat: Formulare-Menü mit Elternbrief-Einstieg + Arbeitsblatt-Personalisierung (Nutzer-Feedback)

Neue Menü-Kategorie "Formulare" in der Menüleiste: "Elternbrief erzeugen..." öffnet
jetzt einen Schüler-Picker statt nur aus der Schülerdetailansicht erreichbar zu sein,
"Arbeitsblatt personalisieren..." ist aktiv, sobald eine einzelne Lerngruppe geöffnet
ist, und erzeugt aus einer in TemplateDesigner gebauten .lavorlage-Vorlage ein PDF je
aktivem Gruppenmitglied - über eine von den Elternbrief-Vorlagen getrennte
WorksheetTemplateStore-Bibliothek.

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

LehrerApp.Desktop/ViewModels/Settings/SettingsViewModel.WorksheetTemplates.cs

@@ -0,0 +1,60 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using LehrerApp.Templating;
+using System.Collections.ObjectModel;
+
+namespace LehrerApp.Desktop.ViewModels.Settings;
+
+public partial class SettingsViewModel
+{
+    [ObservableProperty] private string _worksheetTemplateStatus = "";
+    public ObservableCollection<LetterTemplateListItem> WorksheetTemplateList { get; } = [];
+
+    private void LoadWorksheetTemplates()
+    {
+        WorksheetTemplateList.Clear();
+        foreach (var template in _worksheetTemplates.Store.GetTemplates()) WorksheetTemplateList.Add(CreateWorksheetItem(template));
+    }
+
+    public void ImportWorksheetTemplate(string path)
+    {
+        WorksheetTemplateStatus = "";
+        try
+        {
+            var template = _worksheetTemplates.Store.Import(path);
+            LoadWorksheetTemplates();
+            WorksheetTemplateStatus = $"„{template.Name}“ wurde geprüft und lokal importiert.";
+        }
+        catch (Exception ex) when (ex is IOException or InvalidDataException or UnauthorizedAccessException or TemplateValidationException)
+        { WorksheetTemplateStatus = $"Import fehlgeschlagen: {ex.Message}"; }
+    }
+
+    [RelayCommand]
+    private void ValidateWorksheetTemplate(LetterTemplateListItem? item)
+    {
+        if (item is null) return;
+        try
+        {
+            var refreshed = CreateWorksheetItem(item.Model);
+            var index = WorksheetTemplateList.IndexOf(item);
+            if (index >= 0) WorksheetTemplateList[index] = refreshed;
+            WorksheetTemplateStatus = $"„{item.Name}“ ist gültig (Schema {refreshed.SchemaVersion}).";
+        }
+        catch (Exception ex) when (ex is IOException or InvalidDataException or TemplateValidationException)
+        { WorksheetTemplateStatus = $"„{item.Name}“ ist ungültig: {ex.Message}"; }
+    }
+
+    [RelayCommand]
+    private void DeleteWorksheetTemplate(LetterTemplateListItem? item)
+    {
+        if (item is null) return;
+        _worksheetTemplates.Store.Delete(item.Id); WorksheetTemplateList.Remove(item); WorksheetTemplateStatus = "Vorlage gelöscht.";
+    }
+
+    private LetterTemplateListItem CreateWorksheetItem(InstalledTemplate template)
+    {
+        var loaded = _worksheetTemplates.Store.Load(template);
+        return new(template, loaded.Manifest.SchemaVersion, loaded.Manifest.Placeholders.Count(x => !x.IsConstant),
+            loaded.Manifest.Placeholders.Count(x => !x.IsConstant && x.Required));
+    }
+}

LehrerApp.Desktop/ViewModels/Settings/SettingsViewModel.cs

@@ -62,6 +62,7 @@ public partial class SettingsViewModel : ObservableObject
     private readonly IStudentRepository _students;
     private readonly IShorthandCodeRepository _shorthandCodes;
     private readonly TemplateStore _letterTemplates;
+    private readonly WorksheetTemplateStore _worksheetTemplates;
 
     [ObservableProperty] private int _activeTabIndex;
 
@@ -102,6 +103,7 @@ public partial class SettingsViewModel : ObservableObject
         IShorthandCodeRepository shorthandCodes, ISchoolHolidayRepository schoolHolidays,
         SchoolCalendarSettingsService calendarSettings, PeriodScheduleService periodSchedule,
         ISupervisionDutyRepository supervisionDuties, TemplateStore letterTemplates,
+        WorksheetTemplateStore worksheetTemplates,
         AiSettingsService aiSettings, AiPlanningService aiPlanning, McpSettingsService mcpSettings,
         Services.Mcp.McpClientRegistrationService mcpRegistration,
         WebUntisSettingsService untisSettings,
@@ -139,6 +141,7 @@ public partial class SettingsViewModel : ObservableObject
         _periodSchedule = periodSchedule;
         _supervisionDuties = supervisionDuties;
         _letterTemplates = letterTemplates;
+        _worksheetTemplates = worksheetTemplates;
         _aiSettings = aiSettings;
         _aiPlanning = aiPlanning;
         _mcpSettings = mcpSettings;
@@ -169,6 +172,7 @@ public partial class SettingsViewModel : ObservableObject
         LoadPeriodTimes();
         LoadSupervisionDuties();
         LoadLetterTemplates();
+        LoadWorksheetTemplates();
         LoadAiSettings();
         LoadMcpSettings();
         LoadMcpRegistrationStatus();