chore(release): prepare v0.1.1

[github-actions]

This PR prepares release v0.1.1.

Included

• Refreshes CHANGELOG.md unreleased section
• Points the README.md install snippet at
  v0.1.1
• Validates tests before proposing release prep

The .pre-commit-config.yaml self-pin is not touched here — the tag
does not exist yet, so pinning it would fail this PR's own checks.
The weekly pre-commit autoupdate moves it forward after the tag lands.

Merging this PR creates and pushes the signed tag
v0.1.1 and publishes the release.
No local tagging step is needed.

[michen00]

Closing rather than merging: this PR was generated by the old changelog path and would delete 134 lines of shipped history.

CHANGELOG.md has no ## [0.1.0] section — it jumps from [Unreleased] to [0.0.4] — because nothing in the release pipeline ever converted Unreleased into a versioned section. Everything that shipped in v0.1.0 therefore still lived under Unreleased, and update-unreleased.sh drops that block by design before regenerating it from git cliff --unreleased, which no longer reports those commits now that the tag exists. The result here is 383 lines in, 264 out, with no [0.1.0] section in the output either.

#69 fixes the pipeline: releases now stamp the pending version as its own section, and the regeneration refuses to publish a changelog that is missing that section or has fewer sections than the one it replaces. Once it lands, re-dispatch release-pr and v0.1.1 will regenerate correctly — verified locally to produce 398 lines with [0.1.0] restored and its entries intact.

[github-actions]

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