fix: include SquarePaymentID in commit-failure log for manual reconciliation

backend/handlers/payments/handlers.go

@@ -1067,7 +1067,8 @@ func CreateBookingPayment(w http.ResponseWriter, r *http.Request) {
 	applyEligibleCampaignsAtPayment(r.Context(), tx, bookingID, userID)
 
 	if cErr := tx.Commit(r.Context()); cErr != nil {
-		log.Printf("Failed to commit payment records: %v", cErr)
+		log.Printf("CRITICAL: Square payment %s (ID=%s) was processed but DB transaction commit failed: %v — manual reconciliation required",
+			paymentResult.Status, paymentResult.SquarePayID, cErr)
 		http.Error(w, "internal server error", http.StatusInternalServerError)
 		return
 	}