Add CORS middleware and user database schema

- Implemented CORS middleware in the project to handle cross-origin requests.
- Added necessary files for the CORS package including README, LICENSE, and history documentation.
- Created a SQL schema for the users table with appropriate fields and constraints.
- Inserted mock data into the users table for testing purposes.

backend/package.json

@@ -12,7 +12,10 @@
   "license": "ISC",
   "description": "",
   "dependencies": {
+    "cors": "^2.8.5",
+    "dotenv": "^17.2.0",
     "ejs": "^3.1.10",
-    "express": "^5.1.0"
+    "express": "^5.1.0",
+    "mysql2": "^3.14.2"
   }
 }