Enhance CI and add automated release workflow

[kiro-agent]

This pull request was generated by @kiro-agent 👻

Comment with /kiro fix to address specific feedback or /kiro all to address everything.
_{Learn about Kiro autonomous agent}

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Summary

Enhances the CI pipeline and adds an automated release workflow, modeled after adlio/mixtape.

CI improvements (ci.yml)

• Split into 4 parallel jobs — lint, vet, build, and test+coverage run independently for faster feedback and clearer status checks on PRs
• Removed stale master branch trigger (repo uses main)

Release automation (release.yml)

• Triggered on semver tags (v*.*.*)
• Extracts release notes from CHANGELOG.md using the same awk approach as mixtape
• Creates (or updates) a GitHub Release via gh CLI
• Runs a verification go build + go vet on the tagged commit
• No publish step needed — Go module proxy picks up tags automatically

Changelog (CHANGELOG.md)

• Added in Keep a Changelog format
• Backfilled history for all existing releases (v0.0.1 → v1.0.2)
• Includes comparison links at the bottom for easy diffing

Release workflow

After merging, the release process is:

1. Update CHANGELOG.md — move items from [Unreleased] to a new version section
2. git tag v1.1.0 && git push origin v1.1.0
3. The release workflow creates the GitHub Release with the changelog notes automatically

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (6b8f7c9) to head (3dddaec).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main        #9   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            7         7           
  Lines          216       216           
=========================================
  Hits           216       216           

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