feat: add pending student registration flow and pricing APIs.

Support public class lookup, user provisioning, installment pricing, and admin approval before final enrollment.

constants/registration.js

@@ -0,0 +1,9 @@
+'use strict';
+
+const FULL_PAYMENT_DISCOUNT = 500_000;
+const CLASS_REQUEST_DEPOSIT_RATE = 0.10;
+
+module.exports = {
+  FULL_PAYMENT_DISCOUNT,
+  CLASS_REQUEST_DEPOSIT_RATE
+};