Release first alpha version

[mroczect]

Summary

Tag and publish the first alpha version (v0.1.0-alpha) of the libvctrl crates to crates.io (if public) or prepare an internal release.

Context

An alpha release marks the first usable version of the library and allows early adopters to test the API.

Tasks

• Review the public API of all crates for any unintentional breaks or missing features.
• Update Cargo.toml files:
  • Set version to 0.1.0-alpha.1.
  • Ensure all dependencies are pinned or have appropriate version ranges.
  • Add repository, documentation, keywords, categories, license, readme fields.
• Run cargo publish --dry-run for each crate to verify packaging.
• Create a git tag: git tag -a v0.1.0-alpha.1 -m "Alpha release".
• Publish crates in dependency order: handler, core, plumbing, porcelain.
• Write release notes explaining what is included and known limitations.
• Announce the release in the repository (GitHub Releases, Discussions).

Acceptance Criteria

• All crates are published to crates.io (or internal registry) with version 0.1.0-alpha.1.
• Release notes are available.
• The tag is created and pushed.

Dependencies

• All previous phases (the code must be stable enough for alpha).