Prepare crates.io release

[hypnagonia]

• README: eigentrust = "0.2" and cargo install eigentrust-cli, crates.io and docs.rs badges, link to docs.rs
• CI: the semver check now fails PRs that break the public API without a version bump; additions still pass (checked both cases locally)
• CLAUDE.md: release steps

To be published as eigentrust 0.2.0 and eigentrust-cli 0.2.0.