Add current Fall 2026 recruitment links

[Hilo-Hilo]

Summary

• replace the stale Fall 2026 interest form with the current application link
• publish the current coffee-chat and Linktree destinations on the recruitment page
• update Linktree references across the site and machine-readable metadata
• add exact-link and stale-link build checks

Verification

• 40 tests passed
• changed-file ESLint passed
• production build and SEO validation passed
• desktop and 390 px mobile visual QA passed
• all three destinations returned valid HTTP responses
• independent pre-commit review passed