Add scripts/bump-version.cjs and run it ahead of package:mac/win/linux
so every build gets a fresh patch version. Supports DESKTOP_VERSION for
an explicit version, or major/minor/patch via argument or
DESKTOP_VERSION_BUMP. Version moves 0.1.0 -> 0.1.1.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
