added paid extension boilerplate backend

Author: chinmay29fynd

billing.js

@@ -0,0 +1,27 @@
+const { setupBilling, OrmType } = require("fdk-billing-javascript");
+const mongoose = require('mongoose');
+
+// Connect to MongoDB (using local MongoDB or MongoDB Atlas)
+const MONGODB_URI = process.env.MONGODB_URI || 'mongodb://localhost:27017/fynd-extension-billing';
+
+// Connect to MongoDB (removed deprecated options)
+mongoose.connect(MONGODB_URI)
+.then(() => {
+    console.log('Connected to MongoDB for billing');
+})
+.catch((error) => {
+    console.error('MongoDB connection error:', error);
+});
+
+// Initialize billing instance
+const fdkBillingInstance = setupBilling({
+    extension_id: process.env.EXTENSION_API_KEY,
+    db_connection: mongoose.connection,
+    collection_name: {
+        plan: "plans",
+        subscription: "seller_subscriptions"
+    },
+    orm_type: OrmType.MONGOOSE
+});
+
+module.exports = { fdkBillingInstance }; 

frontend

@@ -22,7 +22,9 @@
     "dotenv": "^16.4.5",
     "express": "^4.19.2",
     "serve-static": "^1.15.0",
-    "sqlite3": "^5.1.7"
+    "sqlite3": "^5.1.7",
+    "fdk-billing-javascript": "github:gofynd/fdk-extension-utils-javascript",
+    "mongoose": "^8.0.0"
   },
   "devDependencies": {
     "axios-mock-adapter": "^1.21.2",