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.Models/RemoteManifest.cs

@@ -56,7 +56,7 @@ public sealed class VersionManifest
     public string Executable { get; set; } = "PROSERVE_UE_5_5.exe";
 
     [JsonPropertyName("installFolderTemplate")]
-    public string InstallFolderTemplate { get; set; } = "Proserve v{version}";
+    public string InstallFolderTemplate { get; set; } = "PROSERVE v{version}";
 
     [JsonPropertyName("download")]
     public DownloadDescriptor Download { get; set; } = new();