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>

server/manifest/versions.json

@@ -9,7 +9,7 @@
       "version": "1.4.6",
       "releasedAt": "2026-04-29T10:00:00Z",
       "executable": "PROSERVE_UE_5_5.exe",
-      "installFolderTemplate": "Proserve v{version}",
+      "installFolderTemplate": "PROSERVE v{version}",
       "download": {
         "url": "https://asterionvr.com/PS_Launcher/builds/proserve-1.4.6.zip",
         "sizeBytes": 0,
@@ -23,7 +23,7 @@
       "version": "1.4.5",
       "releasedAt": "2026-04-15T10:00:00Z",
       "executable": "PROSERVE_UE_5_5.exe",
-      "installFolderTemplate": "Proserve v{version}",
+      "installFolderTemplate": "PROSERVE v{version}",
       "download": {
         "url": "https://asterionvr.com/PS_Launcher/builds/proserve-1.4.5.zip",
         "sizeBytes": 0,