bump version to 0.2.1

[fqjony]

Summary

• Bump to 0.2.1 so the release workflow creates a new GitHub release and tests OIDC npm publish

Test plan

• Release workflow creates v0.2.1 GitHub release
• npm publish succeeds with OIDC provenance

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR bumps the npm package version to 0.2.1 to drive the release workflow (GitHub release + npm publish with OIDC provenance), and records the release notes in the project changelog.

Changes:

• Update package.json version from 0.2.0 → 0.2.1
• Update package-lock.json version fields to 0.2.1
• Add a 0.2.1 section to changes.md

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
package.json	Bumps published package version to 0.2.1.
package-lock.json	Keeps lockfile version metadata in sync with package.json.
changes.md	Adds release notes for 0.2.1.

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