- Add activeDeposit state to BookingDetailPanel via DepositWidget callback
- On checkout, if active deposit (hold_confirmed/paid_cash) exists and balance > 0:
show checkbox 'Зачесть депозит в счёт оплаты' with editable amount
- On confirm: capture deposit via /deposit/release + add booking_payment record
- Default apply amount = min(deposit.amount, outstanding balance)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>