Three fixes applied across all non-working membership types:

1. Sports registration now calculates 50% fee and sends payment request
   to treasury automatically (like Seasonal already did). Also fixed
   billing fallback to find branch pricing without qualification_id.

2. Type-specific CTA now checks if registration record already exists
   in the DB (foreign_member_details, sports_members, etc.) — won't
   reappear after filling the form regardless of billing state.

3. Added duplicate-registration guards to all four type controllers
   (foreign, sports, seasonal, honorary) so users can't accidentally
   submit the registration form twice.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>