- Move auth ALTCHA challenge to /api/v1/auth group
- Move admin ALTCHA challenge to root router before admin login
- Fix route registration issue where endpoints were not accessible
- Add ALTCHA service with challenge generation and verification
- Update auth and admin handlers to use ALTCHA tokens
- Replace Turnstile widget with ALTCHA widget in Flutter app
- Update admin frontend to use ALTCHA token
- Add ALTCHA challenge endpoints for both auth and admin
- Maintain development bypass for testing
- Remove Turnstile dependencies from authentication flow
