feat(loyalty): customer PIN

Adds the 6-digit customer PIN that approves every action moving EnakPoint
or EnakCoin on the customer's request (docs/prd-point-coin.md K8, F11, Q16,
Q17, PC-301).

Migration 000093 adds the PIN columns to customers and the
customer_security_events table. PIN data is read and written only through
CustomerPinRepository, never the Customer entity, so the hash cannot reach
a customer response. Only a bcrypt hash is stored.

- /customer/pin: status, OTP (pin_setup, pin_reset), create, change,
  reset. The OTP must be for that purpose and sent to the customer's own
  number; the existing OTP validation checks neither. A new PIN is checked
  (6 digits, confirmed, not one digit, not a run up or down, not the birth
  date as DDMMYY or YYMMDD) before the OTP is spent.
- Five wrong attempts in a row lock the PIN for 30 minutes; the counter is
  incremented in one statement so attempts at the same time all count,
  and a lock that ran out starts a new series. A locked PIN is refused even
  when right. The customer is told by WhatsApp, as there is no push channel
  to customers yet; only the attempt that reached the limit alerts.
- A reset through OTP lifts the lock and holds outgoing transfers for 24
  hours; paying and exchanging still work, and a held transfer costs no
  attempt.
- VerifyPin(ctx, customer, pin, action) for the flows that follow, with
  PIN_NOT_SET, PIN_INVALID (attempts left), PIN_LOCKED and
  TRANSFER_BLOCKED (until when), which PinErrorResponse turns into
  distinct codes and statuses.
- DELETE /marketing/customers/:id/pin (loyalty managers, reason required)
  and GET /marketing/customers/:id/security-events, scoped to the
  organization.

Every PIN event is in the security log with IP and user agent. No message
or binding error contains a PIN.

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

internal/constants/error.go

@@ -12,6 +12,12 @@ const (
 	ValidationErrorCode     = "304"
 	InvalidFieldErrorCode   = "305"
 	NotFoundErrorCode       = "404"
+	// PIN outcomes the customer app tells apart (docs/prd-point-coin.md §9).
+	PinNotSetErrorCode       = "PIN_NOT_SET"
+	PinInvalidErrorCode      = "PIN_INVALID"
+	PinLockedErrorCode       = "PIN_LOCKED"
+	TransferBlockedErrorCode = "TRANSFER_BLOCKED"
+	TooManyRequestsErrorCode = "429"
 )
 
 const (
@@ -65,15 +71,21 @@ const (
 	CashAdvanceServiceEntity        = "cash_advance_service"
 	WalletServiceEntity             = "wallet_service"
 	LoyaltySettingsServiceEntity    = "loyalty_settings_service"
+	CustomerPinServiceEntity        = "customer_pin_service"
 )
 
 var HttpErrorMap = map[string]int{
-	InternalServerErrorCode: http.StatusInternalServerError,
-	MissingFieldErrorCode:   http.StatusBadRequest,
-	MalformedFieldErrorCode: http.StatusBadRequest,
-	ValidationErrorCode:     http.StatusBadRequest,
-	InvalidFieldErrorCode:   http.StatusBadRequest,
-	NotFoundErrorCode:       http.StatusNotFound,
+	InternalServerErrorCode:  http.StatusInternalServerError,
+	MissingFieldErrorCode:    http.StatusBadRequest,
+	MalformedFieldErrorCode:  http.StatusBadRequest,
+	ValidationErrorCode:      http.StatusBadRequest,
+	InvalidFieldErrorCode:    http.StatusBadRequest,
+	NotFoundErrorCode:        http.StatusNotFound,
+	PinNotSetErrorCode:       http.StatusForbidden,
+	PinInvalidErrorCode:      http.StatusBadRequest,
+	PinLockedErrorCode:       http.StatusLocked,
+	TransferBlockedErrorCode: http.StatusForbidden,
+	TooManyRequestsErrorCode: http.StatusTooManyRequests,
 }
 
 // Error messages