Critical fixes:
- submitFormPayment() now checks sa_players.registration_fee_paid as
  a safety net before creating any payment request
- startRegistration() member_id fallback only used when NID matches
  the member's actual national_id (prevents NID-swap fee bypass)
- lookupPlayer() validates NID-to-member consistency before proceeding
- Existing registration lookup now includes 'pending_payment' status
- Frontend clears membership_number when NID is manually changed
  after auto-fill

Feature:
- Player profile page now shows "Print Form" and "Generate Card"
  buttons for completing registration steps outside the wizard
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>