- Install github.com/altcha-org/altcha-lib-go official library
- Replace custom implementation with official ALTCHA methods
- Use CreateChallenge for proper cryptographic challenges
- Use VerifySolution for proper token verification
- This should fix all ALTCHA verification issues
- 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
