Closes#10. A GitHub Action bot with no server: one triage comment per
new issue (classification, missing-info list, grounded first answer),
answers comments that @artex-bot, and a first-look summary checklist on
opened pull requests. Comment-only, never an approving review. Skips
the maintainer, bots, and itself; exits cleanly without the API key;
all model inputs are size-capped.
