docs: add CHANGELOG.md with 4.4.2 release notes

[mherod]

Summary

• Adds CHANGELOG.md to the project root
• Documents the two user-facing changes shipped in v4.4.2: Bun runtime support (feat: add Bun runtime support with SQLite adapter abstraction #422) and the Node.js ESM import fix (fix: guard BunSqliteAdapter against Node.js ESM environments #423)

Test plan

• No code changes — docs only
• Verify CHANGELOG.md renders correctly on GitHub

[claude]

PR Review: CHANGELOG.md for v4.4.2

Overview

Adds a new CHANGELOG.md documenting the two user-facing changes shipped in v4.4.2. Docs-only, no code risk.

Findings

🔵 Suggestions

• Consider adding version comparison links at the bottom (common in Keep a Changelog format), e.g.:
  [4.4.2]: https://github.com/mherod/get-cookie/compare/v4.4.1...v4.4.2
  This makes it easy for users to browse the full diff for each release directly from the changelog.

👍 What's Good

• Date (2026-02-20) matches the actual release date
• PR/issue cross-references (#422, #423, #419) are included
• New Features / Bug Fixes categorisation is accurate and clear
• Prose descriptions are concise and informative

Summary

LGTM. The suggestion above is a nice-to-have for future releases rather than a blocker here.