release: bump version to 0.2.3

[SF-Zhou]

Finalize the changelog: rename Unreleased to 0.2.3 (2026-07-16) and add the compare link. All changes since 0.2.2 are additive or internal; no breaking changes.

[Copilot]

Pull request overview

This PR finalizes the 0.2.3 release metadata by updating the crate version and promoting the changelog’s top section from “Unreleased” to the 0.2.3 release entry with an appropriate compare link.

Changes:

• Update Cargo.toml package version from 0.2.2 to 0.2.3.
• Rename the changelog “Unreleased” section to 0.2.3 with the release date 2026-07-16.
• Add the [0.2.3] GitHub compare link (v0.2.2...v0.2.3) to the changelog reference links.

Reviewed changes

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

File	Description
CHANGELOG.md	Finalizes the 0.2.3 changelog entry and adds the compare link reference.
Cargo.toml	Bumps crate version to 0.2.3 for the release.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.29%. Comparing base (4f28492) to head (fd24bec).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #44   +/-   ##
=======================================
  Coverage   99.29%   99.29%           
=======================================
  Files           3        3           
  Lines        2272     2272           
=======================================
  Hits         2256     2256           
  Misses         16       16           

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