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/Views/MainWindow.xaml

@@ -371,7 +371,7 @@
 
                             <!-- Numéro version + badge -->
                             <StackPanel Grid.Row="1" Grid.Column="0" Orientation="Horizontal" VerticalAlignment="Center">
-                                <TextBlock Text="{Binding FeaturedVersion.Version, StringFormat='Proserve v{0}'}"
+                                <TextBlock Text="{Binding FeaturedVersion.Version, StringFormat='PROSERVE v{0}'}"
                                            FontSize="32" FontWeight="Bold"
                                            Foreground="{StaticResource Brush.Text.Primary}" />
                                 <Border CornerRadius="12" Padding="10,4" Margin="16,8,0,0"