feat(loyalty): remove paying with EnakPoint

EnakPoint can only be redeemed for vouchers now: it can no longer pay for
orders and is never cashed out (docs/enakgame-prd.md §3.2, EG-001,
EG-002). No order was ever paid with EnakPoint, so there is no data to
move.

Removed:
- POST /customer/wallet/payment-code, POST /customer/orders/:id/pay-with-points
  and GET /orders/:id/point-payment/preview, with their processors,
  repositories, services, handlers and tests.
- The point payment method type: paying, splitting and refunding with it,
  the outlet filter on the method list, and the system-method guard.
- points and payment_code on CreatePayment; points_used and point_value
  on payments; accepts_point_payment on the customer outlets.
- The outlet point_payment settings. A PUT that still sends them is
  rejected as an unknown field.
- The EnakPoint split in the payment method analytics.
- PAYMENT and PAYMENT_REFUND from the wallet type rules. Tests that used
  them as a generic EnakPoint debit use REWARD_REDEEM.
- The EnakPoint-paid part from the earning basis, which is
  subtotal − discount again.

Migration 000102 drops the trigger, the point methods and their index,
the payments columns, and the outlet settings, and restores the method
type CHECK without point. payments.payment_method_id is ON DELETE
RESTRICT, so it fails rather than lose a payment made with EnakPoint.

The integration docs list the removed endpoints and fields, and the
EnakPoint & EnakCoin PRD and tasks note what is superseded.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/constants/loyalty.go

@@ -4,7 +4,7 @@ package constants
 // outlet_settings and organization keys in organization_settings. A key that was
 // never set takes the default in the PRD.
 
-// Per outlet (F1): what an order earns, and whether EnakPoint can pay.
+// Per outlet (F1): what an order earns.
 const (
 	LoyaltyPointEnabledKey        = "loyalty.point.enabled"
 	LoyaltyPointEarnModeKey       = "loyalty.point.earn_mode"
@@ -21,10 +21,6 @@ const (
 	LoyaltyCoinEarnValueKey      = "loyalty.coin.earn_value"
 	LoyaltyCoinMinOrderAmountKey = "loyalty.coin.min_order_amount"
 	LoyaltyCoinMaxPerOrderKey    = "loyalty.coin.max_per_order"
-
-	LoyaltyPointAcceptPaymentKey     = "loyalty.point.accept_payment"
-	LoyaltyPointMinPaymentPointsKey  = "loyalty.point.min_payment_points"
-	LoyaltyPointMaxPaymentPercentKey = "loyalty.point.max_payment_percent"
 )
 
 // Per organization (F2, F12): the value of EnakPoint, the exchange rate, transfers and
@@ -81,9 +77,6 @@ const (
 	LoyaltyEarnModeDefault           = LoyaltyEarnModePerAmount
 	LoyaltyEarnPercentDefault        = float64(1)
 
-	LoyaltyMinPaymentPointsDefault  = int64(1)
-	LoyaltyMaxPaymentPercentDefault = int64(100)
-
 	LoyaltyPointValueDefault     = int64(1)
 	LoyaltyExchangeAmountDefault = int64(1)