Keep llms.txt aligned before deployment

[Hilo-Hilo]

Summary

• bring public/llms.txt up to date with the complete Fall 2026 recruitment schedule and current application, coffee-chat, newsletter, and Linktree destinations
• align public/agent-instructions.md with the current Join Us page
• add regression assertions for machine-readable recruitment facts
• add a permanent pre-deployment llms.txt review guideline to the README and pull-request template

Pre-deployment checklist

• Reviewed changed public facts, links, route descriptions, and capability claims against public/llms.txt, and updated it where affected.
• Reviewed public/agent-instructions.md; public/developers.md needs no change because technical capabilities are unchanged.
• npm test passes: 40/40.
• npm run build passes, including SEO and machine-readable content checks.
• Live verification targets identified: /signup/, /llms.txt, and /agent-instructions.md.