feat: Implement get subscription API endpoint

packages/backend/test/factories/subscription.js

@@ -0,0 +1,21 @@
+import { DateTime } from 'luxon';
+import { createUser } from './user';
+import Subscription from '../../src/models/subscription.ee.js';
+
+export const createSubscription = async (params = {}) => {
+  params.userId = params?.userId || (await createUser()).id;
+  params.paddleSubscriptionId =
+    params?.paddleSubscriptionId || 'paddleSubscriptionId';
+
+  params.paddlePlanId = params?.paddlePlanId || '47384';
+  params.updateUrl = params?.updateUrl || 'https://example.com/update-url';
+  params.cancelUrl = params?.cancelUrl || 'https://example.com/cancel-url';
+  params.status = params?.status || 'active';
+  params.nextBillAmount = params?.nextBillAmount || '20';
+  params.nextBillDate =
+    params?.nextBillDate || DateTime.now().plus({ days: 30 }).toISODate();
+
+  const subscription = await Subscription.query().insert(params).returning('*');
+
+  return subscription;
+};