feat(dimentorin): payment module - gateway-agnostic VA/QRIS with admin confirm
- app_payments table + PaymentEntity (amount from mentor mentoring_rate + service fee 2000)
- PaymentRepository (postgres) + PaymentServiceImpl (create/get/confirm/list)
- Routes: POST /payments/sessions/{id}/create, GET /payments/me, GET /payments/{id}, POST /payments/{id}/confirm
- confirm guarded by Admin/Admin Pembayaran role; ownership guard mentee-only view
- provider=manual default (swap midtrans/xendit later), e2e verified: VA+QRIS create, confirm 200, re-confirm 409, non-admin 403, foreign payment 403
asepharyana
444c98074f