Initial commit: EngineeringSync v1.0.0

Vollständige Implementierung des EngineeringSync-Middleware-Tools:
- Windows Service (Kestrel :5050) mit FileSystemWatcher + SignalR
- WPF Tray-App mit PendingChanges- und Projektverwaltungs-Fenster
- Setup-Wizard (8-Schritte-Installer)
- SQLite/EF Core Datenschicht (WAL-Modus)
- SHA-256-basiertes Debouncing (2s Fenster)
- Backup-System mit konfigurierbarer Aufbewahrung

Bugfixes & Verbesserungen:
- BUG-1: AppDbContext OnConfiguring invertierte Bedingung behoben
- BUG-2: Event-Handler-Leak in TrayApp (Fenster-Singleton-Pattern)
- BUG-3: ProjectConfigChanged SignalR-Signal in allen CRUD-Endpoints
- BUG-5: Rename-Sync löscht alte Datei im Simulations-Ordner
- BUG-6: Doppeltes Dispose von SignalR verhindert
- BUG-7: Registry-Deinstallation nur EngineeringSync-Eintrag entfernt
- S1: Path-Traversal-Schutz via SafeCombine() im SyncManager
- E1: FSW Buffer 64KB + automatischer Re-Scan bei Overflow
- E2: Retry-Logik (3x) für gesperrte Dateien mit exponentiellem Backoff
- E4: Channel.Writer.TryComplete() beim Shutdown
- C2: HubMethodNames-Konstanten statt Magic Strings
- E3: Pagination in Changes-API (page/pageSize Query-Parameter)
- A1: Fire-and-Forget mit try/catch + Logging

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

EngineeringSync.Setup/ViewModels/WizardViewModel.cs

@@ -0,0 +1,135 @@
+using System.Collections.ObjectModel;
+using System.Windows;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using EngineeringSync.Setup.Services;
+using EngineeringSync.Setup.Views.Pages;
+
+namespace EngineeringSync.Setup.ViewModels;
+
+public partial class WizardViewModel : ObservableObject
+{
+    public WizardState State { get; } = new();
+
+    [ObservableProperty] private WizardPageBase _currentPage = null!;
+    [ObservableProperty] private int _currentStepIndex;
+    [ObservableProperty] private bool _canGoBack;
+    [ObservableProperty] private bool _canGoNext = true;
+    [ObservableProperty] private bool _isLastStep;
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ShowNextButton))]
+    private bool _isInstalling;
+
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ShowNextButton))]
+    private bool _isCompleted;
+
+    public bool ShowNextButton => !IsCompleted && !IsInstalling;
+
+    public ObservableCollection<WizardStep> Steps { get; } =
+    [
+        new("Willkommen",    "\uE80F"),   // Home icon
+        new("Installation",  "\uE7B7"),   // Folder icon
+        new("Erstes Projekt","\uE8B7"),   // Link icon
+        new("Backup",        "\uE72E"),   // Save icon (NEU)
+        new("Optionen",      "\uE713"),   // Settings icon
+        new("Zusammenfassung","\uE8A9"),  // List icon
+        new("Installation",  "\uE896"),   // Download icon
+        new("Fertig",        "\uE930"),   // Completed icon
+    ];
+
+    private readonly List<Func<WizardPageBase>> _pageFactories;
+    private readonly InstallerService _installer;
+
+    public WizardViewModel()
+    {
+        _installer = new InstallerService(State);
+
+        _pageFactories =
+        [
+            () => new WelcomePage(this),
+            () => new InstallPathPage(this),
+            () => new FirstProjectPage(this),
+            () => new BackupOptionsPage(this),    // NEU – Index 3
+            () => new ServiceOptionsPage(this),
+            () => new SummaryPage(this),
+            () => new InstallingPage(this, _installer),
+            () => new CompletionPage(this),
+        ];
+
+        NavigateTo(0);
+    }
+
+    public void NavigateTo(int index)
+    {
+        CurrentStepIndex = index;
+        CurrentPage = _pageFactories[index]();
+        Steps[index].IsActive = true;
+
+        for (int i = 0; i < Steps.Count; i++)
+        {
+            Steps[i].IsCompleted = i < index;
+            Steps[i].IsActive    = i == index;
+        }
+
+        CanGoBack   = index > 0 && index < Steps.Count - 1 && !IsInstalling;
+        IsLastStep  = index == Steps.Count - 2; // "Zusammenfassung" ist letzter normaler Schritt
+        // IsInstalling wird NICHT hier gesetzt – wird von InstallingPage kontrolliert
+        IsCompleted  = index == Steps.Count - 1;
+        CanGoNext   = !IsInstalling && !IsCompleted;
+    }
+
+    public void SetInstallingState(bool installing)
+    {
+        IsInstalling = installing;
+        // CanGoNext wird durch die Bedingung !IsInstalling && !IsCompleted neu evaluiert
+        CanGoNext = !IsInstalling && !IsCompleted;
+        // GoBackCommand und CancelCommand CanExecute Bedingungen neu evaluieren
+        GoBackCommand.NotifyCanExecuteChanged();
+        CancelCommand.NotifyCanExecuteChanged();
+    }
+
+    [RelayCommand(CanExecute = nameof(CanExecuteGoBack))]
+    private void GoBack() => NavigateTo(CurrentStepIndex - 1);
+
+    private bool CanExecuteGoBack => CanGoBack && !IsInstalling;
+
+    [RelayCommand]
+    private void GoNext()
+    {
+        if (!CurrentPage.Validate()) return;
+        if (CurrentStepIndex < _pageFactories.Count - 1)
+            NavigateTo(CurrentStepIndex + 1);
+    }
+
+    [RelayCommand(CanExecute = nameof(CanExecuteCancel))]
+    private void Cancel()
+    {
+        if (IsCompleted) return;
+        var result = MessageBox.Show(
+            "Setup wirklich abbrechen?",
+            "EngineeringSync Setup",
+            MessageBoxButton.YesNo,
+            MessageBoxImage.Question);
+        if (result == MessageBoxResult.Yes)
+            Application.Current.Shutdown();
+    }
+
+    private bool CanExecuteCancel => !IsInstalling && !IsCompleted;
+
+    [RelayCommand]
+    private void Finish()
+    {
+        if (State.StartAfterInstall)
+            _installer.LaunchTrayApp();
+        Application.Current.Shutdown();
+    }
+}
+
+public partial class WizardStep(string title, string icon) : ObservableObject
+{
+    public string Title { get; } = title;
+    public string Icon  { get; } = icon;
+    [ObservableProperty] private bool _isActive;
+    [ObservableProperty] private bool _isCompleted;
+}