v0.13.0 — Report tool : timestamped backups + manual revert

The previous deploy mechanism kept the old version under {target}.old
just long enough to swap, then deleted it — no way back if the new
report had a runtime bug only visible at use time.

Now each deploy keeps the previous active version under
{FolderName}.backup-yyyyMMdd-HHmmss/. The N most recent are kept
(MaxBackups, default 3) and older ones are pruned in best-effort.

UI in Settings → Avancés → Outil Report :
- "Conserver N backups" input (0 = no history, back to v0.12 behavior)
- List of backups with date + size + cryptic folder name + per-row "↶ Revert"
- Confirmation dialog: "Revert to {date}? The currently deployed
  version will itself be saved as a new backup, so you can switch back."

Implementation
- IReportToolDeployer: + ListBackupsAsync, + RevertAsync, + BackupInfo,
  + DeployStatus.BackupNotFound.
- ReportToolDeployer: deploy renames {target} → backup-{ts}; PruneOldBackups
  trims to MaxBackups; RevertAsync atomically swaps current ↔ chosen
  backup, the previous current becoming itself a fresh backup.
- ReportBackupViewModel + DataTemplate for the list rows.
- Strings: backup labels, "↶ Revert", confirmation message.

Caveats documented in the design discussion:
- Backups cover ONLY the report tool files. DB migrations are not reverted
  (irreversible). If a migration broke the schema, that's a separate fix.
- No HTTP-HEAD post-deploy auto-revert: too fragile for false positives.
  Revert stays a deliberate manual action.

Versions bumped to 0.13.0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/PSLauncher.App/ViewModels/SettingsViewModel.cs

@@ -63,8 +63,12 @@ public sealed partial class SettingsViewModel : ObservableObject
     [ObservableProperty] private string _reportHtdocsRoot;
     [ObservableProperty] private string _reportFolderName;
     [ObservableProperty] private bool _reportAutoDeploy;
+    [ObservableProperty] private int _reportMaxBackups;
     [ObservableProperty] private string? _reportDeployStatus;
     [ObservableProperty] private bool _isDeployingReport;
+    public System.Collections.ObjectModel.ObservableCollection<ReportBackupViewModel> ReportBackups { get; }
+        = new();
+    public bool HasReportBackups => ReportBackups.Count > 0;
 
     public IReadOnlyList<LanguageOption> AvailableLanguages { get; } =
         PSLauncher.Core.Localization.Strings.Available
@@ -164,6 +168,9 @@ public sealed partial class SettingsViewModel : ObservableObject
         _reportHtdocsRoot = config.ReportTool.HtdocsRoot;
         _reportFolderName = config.ReportTool.FolderName;
         _reportAutoDeploy = config.ReportTool.AutoDeploy;
+        _reportMaxBackups = config.ReportTool.MaxBackups;
+        // Charge la liste de backups en arrière-plan (UI immédiate puis remplie quand prête)
+        _ = LoadReportBackupsAsync();
 
         LauncherVersion = Assembly.GetExecutingAssembly().GetName().Version?.ToString() ?? "0.0.0";
         MachineId = licenseService.GetMachineId();
@@ -287,6 +294,7 @@ public sealed partial class SettingsViewModel : ObservableObject
         _config.ReportTool.HtdocsRoot = ReportHtdocsRoot.Trim();
         _config.ReportTool.FolderName = ReportFolderName.Trim();
         _config.ReportTool.AutoDeploy = ReportAutoDeploy;
+        _config.ReportTool.MaxBackups = Math.Max(0, ReportMaxBackups);
 
         _configStore.Save(_config);
         _logger.LogInformation("Settings saved (language={Lang}, changed={Changed})", _config.Language, languageChanged);
@@ -494,4 +502,76 @@ public sealed partial class SettingsViewModel : ObservableObject
             IsReplayingMigrations = false;
         }
     }
+
+    // ===================== REPORT TOOL BACKUPS =====================
+
+    private async Task LoadReportBackupsAsync()
+    {
+        try
+        {
+            var list = await _reportDeployer.ListBackupsAsync(CancellationToken.None);
+            ReportBackups.Clear();
+            foreach (var b in list)
+                ReportBackups.Add(new ReportBackupViewModel(b, RevertReportToBackupAsync));
+            OnPropertyChanged(nameof(HasReportBackups));
+        }
+        catch (Exception ex)
+        {
+            _logger.LogDebug(ex, "Could not list report backups");
+        }
+    }
+
+    /// <summary>Appelé par chaque ligne du tableau de backups via son own command.</summary>
+    private async Task RevertReportToBackupAsync(BackupInfo backup)
+    {
+        var localDate = backup.TimestampUtc.ToLocalTime();
+        var dateLabel = Strings.FormatLongDate(localDate);
+        var confirm = MessageBox.Show(
+            Strings.MsgRevertReportConfirm(dateLabel),
+            Strings.MsgBoxRevertReport,
+            MessageBoxButton.YesNo, MessageBoxImage.Question, MessageBoxResult.No);
+        if (confirm != MessageBoxResult.Yes) return;
+
+        IsDeployingReport = true;
+        ReportDeployStatus = $"Revert vers {dateLabel}…";
+        try
+        {
+            var result = await _reportDeployer.RevertAsync(backup.FolderName, CancellationToken.None);
+            ReportDeployStatus = result.Status == DeployStatus.Deployed
+                ? Strings.MsgRevertReportSuccess(dateLabel)
+                : $"✗ {result.ErrorMessage}";
+            await LoadReportBackupsAsync();
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Revert report failed");
+            ReportDeployStatus = $"✗ {ex.Message}";
+        }
+        finally
+        {
+            IsDeployingReport = false;
+        }
+    }
+}
+
+/// <summary>
+/// Ligne du tableau "Backups disponibles" dans Settings → Avancés → Outil Report.
+/// Chaque instance porte sa propre commande Revert paramétrée pour ce backup.
+/// </summary>
+public sealed partial class ReportBackupViewModel : ObservableObject
+{
+    public BackupInfo Info { get; }
+    public string DateDisplay => Strings.FormatLongDate(Info.TimestampUtc.ToLocalTime());
+    public string SizeDisplay => Strings.SettingsReportBackupSize(Strings.FormatSize(Info.SizeBytes));
+    public string FolderName => Info.FolderName;
+
+    private readonly Func<BackupInfo, Task> _revertHandler;
+    public ReportBackupViewModel(BackupInfo info, Func<BackupInfo, Task> revertHandler)
+    {
+        Info = info;
+        _revertHandler = revertHandler;
+    }
+
+    [RelayCommand]
+    private Task Revert() => _revertHandler(Info);
 }