Brand: install folder uses uppercase PROSERVE v{version}

The product wordmark is rendered uppercase everywhere in the UI
(PROSERVE in Pirulen). Align the install directory naming so it reads
"PROSERVE v1.4.7" instead of "Proserve v1.4.7" — same brand, same case
on disk and in dialog titles.

Changes:
- server/manifest/versions.json: installFolderTemplate updated for both
  existing entries.
- server/admin/versions.php: default template for new versions added
  via the backoffice form.
- src/PSLauncher.Models/RemoteManifest.cs: default fallback for the
  property when missing from JSON.
- src/PSLauncher.App/Views/MainWindow.xaml + dialogs + ViewModel
  toasts: UI strings now read "PROSERVE v..." consistent with the brand.

InstallationRegistry's regex was already RegexOptions.IgnoreCase, so
existing user installs in "Proserve v..." folders keep working
(case-insensitive on Windows filesystems anyway). Re-installing an
older version after the change re-creates the folder with the new
case — Windows is case-preserving but case-insensitive, so launching
remains identical.

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

src/PSLauncher.App/ViewModels/MainViewModel.cs

@@ -135,7 +135,7 @@ public sealed partial class MainViewModel : ObservableObject
     public string EmptyHint =>
         "Aucune version locale ni distante.\n" +
         "Clique « Vérifier les mises à jour » pour récupérer le catalogue depuis le serveur, " +
-        "ou place un dossier « Proserve v{X.Y.Z} » contenant PROSERVE_UE_5_5.exe dans :\n" +
+        "ou place un dossier « PROSERVE v{X.Y.Z} » contenant PROSERVE_UE_5_5.exe dans :\n" +
         _config.InstallRoot;
 
     public Visibility EmptyHintVisibility =>
@@ -439,7 +439,7 @@ public sealed partial class MainViewModel : ObservableObject
                 proc.EnableRaisingEvents = true;
                 proc.Exited += (_, _) =>
                 {
-                    _logger.LogInformation("Proserve v{Version} a quitté — restauration du launcher", row.Version);
+                    _logger.LogInformation("PROSERVE v{Version} a quitté — restauration du launcher", row.Version);
                     Application.Current?.Dispatcher.Invoke(() =>
                     {
                         if (Application.Current.MainWindow is { } main)
@@ -539,7 +539,7 @@ public sealed partial class MainViewModel : ObservableObject
             RebuildList();
             _toastService.ShowSuccess(
                 "Installation terminée",
-                $"Proserve v{row.Version} est prête à être lancée.");
+                $"PROSERVE v{row.Version} est prête à être lancée.");
         }
         catch (OperationCanceledException)
         {