Add rustup installer batch file for the Windows 11 VM

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

seediso/windows11/Install-Rustup.bat

@@ -0,0 +1,30 @@
+@echo off
+setlocal
+title Install Rust toolchain (rustup)
+
+rem rustup installs per user (%USERPROFILE%\.cargo), so run this as the user who will use Rust.
+rem The default msvc toolchain needs the MSVC Build Tools (see Install-MSVC2022-BuildTools.bat).
+
+set "INSTALLER=%TEMP%\rustup-init.exe"
+
+echo Downloading rustup-init...
+curl.exe -L --fail -o "%INSTALLER%" https://win.rustup.rs/x86_64
+if errorlevel 1 (
+    echo Download failed.
+    pause
+    exit /b 1
+)
+
+echo Installing the stable Rust toolchain...
+"%INSTALLER%" -y --default-toolchain stable --profile default
+set "RC=%ERRORLEVEL%"
+
+del "%INSTALLER%" >nul 2>&1
+
+if "%RC%"=="0" (
+    echo Done. Open a new terminal to pick up the updated PATH.
+) else (
+    echo rustup-init exited with code %RC%.
+)
+pause
+exit /b %RC%