Release 0.1.0a2 #97

The maintainer approved a version bump (2026-10-04, relayed by the ecosystem lead). It bumps pyproject.toml to 0.1.0a2 and updates the install lines (README en/ko, guide, AGENTS and style examples). It then publishes the GitHub pre-release v0.1.0a2, which runs publish-pypi.

Done when 0.1.0a2 is on PyPI, a clean venv installs it with uv, and import pythonx.compose succeeds. The release notes must say it needs python-multiplatform develop with #146 and #168 or later.