feat(loyalty): remind customers before balances expire

Adds what the customer sees of expiry (docs/prd-point-coin.md F6, F12,
PC-504).

GET /customer/wallet/expiring lists everything that will expire, per
currency and day, soonest first. GET /customer/wallet already had the
nearest expiry per currency.

The expiry job now also sends reminders, with the settings of note N4 as
decided: once, reminder_days before (7 by default, 0 for none), per
currency. A customer gets one FCM push per currency and expiry day,
however many lots make it up: "150 EnakPoint akan kedaluwarsa pada 31 Okt
2026. Pakai sebelum hangus.", with type WALLET_EXPIRING, the currency,
amount and expiry_date in its data. Reminders cover whatever falls within
the window, so a run that was missed catches up rather than skipping a day.

Migration 000097 adds wallet_expiry_reminders, one row per customer,
currency and expiry day. The row is written before the push is sent, so
several instances of the job or a restart never remind twice; a push that
then fails is logged and not retried. Lots that expire later on the same
day as an earlier reminder are not reminded of again.

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

internal/router/router.go

@@ -172,6 +172,7 @@ func (r *Router) addAppRoutes(rg *gin.Engine) {
 			customer.GET("/tokens", r.customerPointsHandler.GetCustomerTokens)
 			customer.GET("/wallet", r.customerPointsHandler.GetCustomerWallet)
 			customer.GET("/wallet/transactions", r.customerPointsHandler.GetCustomerWalletTransactions)
+			customer.GET("/wallet/expiring", r.customerPointsHandler.GetCustomerWalletExpiring)
 			customer.POST("/wallet/payment-code", r.customerPinHandler.IssuePaymentCode)
 			customer.GET("/wallet/exchange/preview", r.customerWalletHandler.PreviewExchange)
 			customer.POST("/wallet/exchange", r.customerWalletHandler.Exchange)

internal/router/router_test.go

@@ -28,6 +28,7 @@ func TestAllRoutesRegister(t *testing.T) {
 	for _, want := range []string{
 		"GET /api/v1/customer/wallet",
 		"GET /api/v1/customer/wallet/transactions",
+		"GET /api/v1/customer/wallet/expiring",
 		"GET /api/v1/marketing/customers/:id/wallet",
 		"POST /api/v1/marketing/customers/:id/wallet/adjust",
 		"GET /api/v1/marketing/wallet-transactions/:id/trace",