* Fix Windows build flow
* build(makefile): make windows recipes shell-safe
- avoid backslash line-continuation in Windows build-launcher recipe
- replace cmd-specific if-not-exist with PowerShell check in web build-frontend
* Fix Windows build flow
* build(makefile): make windows recipes shell-safe
- avoid backslash line-continuation in Windows build-launcher recipe
- replace cmd-specific if-not-exist with PowerShell check in web build-frontend
* build(web): avoid shell-expanding powershell vars in windows recipe
- rewrite build-frontend Windows command without PowerShell local vars
- keep install-stamp hash check logic
