chore: release version 2.5.4 🚀

- **🧹 Chores**
  - Promote the package version to `2.5.4` and update the changelog with release notes.
  - Correct the recorded date for version `2.5.2`.

- **📝 Documentation**
  - Update the README and marketplace documentation to highlight Anthropic prompt caching, cache usage reporting, safer retries, and improved test isolation.