v0.1.0

Add cross-platform build and distribution

Tag-driven release pipeline that builds native binaries for macOS (arm64/x64),
Linux (arm64/x64), and Windows (x64), uploads archives + SHA-256 checksums to
the GitHub release, and publishes a Homebrew formula and Scoop manifest to their
taps (skipped gracefully without TAP_TOKEN). Adds a CI checks workflow and
single-sources the version from pubspec.

- tool/: build_release (compile + archive + sha256), sync_version, read_version,
  Homebrew/Scoop renderers
- .github/workflows: ci.yml (format/analyze/test), release-binaries.yml
- --version flag backed by generated lib/src/version.dart
- MIT LICENSE, README install section, docs/RELEASING.md