Packaging: Windows MSI gets a setup wizard with version and launch box

Double-clicking the MSI used to flash a progress bar and close, so users couldn't tell it had
installed. It now opens a wizard: Welcome, install folder (remembered across upgrades), Ready,
progress, and a Finish page that says where to find the app with a ticked "Launch VectorCraft"
box. Every page names the full version, pre-release tag included. The wizard art is drawn from
the app icon at package time; msiexec /qn still installs silently.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/release.yml

@@ -148,7 +148,9 @@ jobs:
         run: cargo xtask version set "$VECTORCRAFT_VERSION"
       - name: Install WiX
         shell: pwsh
-        run: dotnet tool install --global wix --version 5.0.2
+        run: |
+          dotnet tool install --global wix --version 5.0.2
+          wix extension add -g WixToolset.UI.wixext/5.0.2 WixToolset.Util.wixext/5.0.2
       - name: Build, sign, package
         shell: pwsh
         env: