Add shared export infrastructure

LehrerApp.Desktop/ViewModels/Groups/ReportGradeViewModels.cs

@@ -3,9 +3,9 @@ using CommunityToolkit.Mvvm.Input;
 using LehrerApp.Core.Interfaces;
 using LehrerApp.Core.Models;
 using LehrerApp.Core.Services;
+using LehrerApp.Desktop.Services;
 using System.Collections.ObjectModel;
 using System.Globalization;
-using System.Text;
 
 namespace LehrerApp.Desktop.ViewModels.Groups;
 
@@ -197,12 +197,13 @@ public partial class ReportGradeDialogViewModel : ObservableObject
 
     public string ExportCsv()
     {
-        var sb = new StringBuilder();
-        sb.AppendLine($"Zeugnisnoten;{_groupLabel};{SelectedPeriod.Label}");
-        sb.AppendLine("Schüler;Berechnet;Übersteuert;Begründung;Endnote;Gesperrt");
+        var csv = new CsvBuilder()
+            .AddRow("Zeugnisnoten", _groupLabel, SelectedPeriod.Label)
+            .AddRow("Schüler", "Berechnet", "Übersteuert", "Begründung", "Endnote", "Gesperrt");
         foreach (var r in Rows)
-            sb.AppendLine($"{r.Name};{r.CalculatedValue};{r.OverrideValue};{r.OverrideReason};{r.FinalDisplay};{(r.IsLocked ? "ja" : "")}");
-        return sb.ToString();
+            csv.AddRow(r.Name, r.CalculatedValue, r.OverrideValue, r.OverrideReason,
+                r.FinalDisplay, r.IsLocked ? "ja" : "");
+        return csv.ToString();
     }
 
 }