docs: add Gemini CLI appendix to primitives matrix(#202)

[Mahizhan-S]

Summary

Added Gemini CLI support to the loop primitives documentation.

Changes

• Added a new ## Appendix: Gemini CLI section in docs/primitives-matrix.md.

• Mapped loop primitives to Gemini CLI workflows:

  • scheduling using cron/systemd/GitHub Actions
  • skills and context files (GEMINI.md)
  • state management using STATE.md.example
  • maker/checker workflow using separate sessions
  • week-one Daily Triage workflow

• Added a Gemini CLI entry in examples/README.md.

Since there is currently no dedicated examples/gemini-cli/ directory, the README entry links directly to the Gemini CLI appendix in primitives-matrix.md, similar to the existing Aider CLI documentation approach.

Testing

Documentation-only change.

[github-actions]

Thanks @Mahizhan-S for contributing a tool example — visible, reviewable PRs like this grow the reference for everyone.

What happens next

• Maintainer aims for same-day review on story, adopter, and scoped docs/example PRs (CONTRIBUTING.md).
• good first issue PRs: comment on the linked issue so we can assign and close on merge.

More ways to help

• Contributor quickstart + open issues
• Good first issue backlog

— loop-engineering maintainers