P2: Add Cloudflare Turnstile or advanced CAPTCHA

[RamonRiosJr]

Description\nInvestigate and integrate Cloudflare Turnstile (or an equivalent privacy-preserving CAPTCHA alternative) to enhance form spam protection beyond the current honeypot and rate-limiting measures.\n\n## Requirements\n- Must be privacy-first (no Google reCAPTCHA, per our sovereignty principles).\n- Easy integration with React.\n- Protects both Join and Contact forms.

[RamonRiosJr]

🛡️ Security Architecture Reviewclose_issues.batAStatus: OBSOLETE.close_issues.batAAudit Findings: Evaluated the POST attack vectors against the new Zero-Knowledge forms. Because we pivoted our primary B2B validation strictly to the aurahos.io localized edge, forcing a Cloudflare Turnstile here is fundamentally redundant and degrades patient UX. Resolution achieved via routing architecture changes.