Centralize CORS configuration for Express and Socket.IO using .env

[tusharnain]

Centralize CORS configuration for Express and Socket.IO using .env

Description

This pull request centralizes the CORS configuration for both Express and Socket.IO into a single reusable module.
It introduces environment-based origin management using the .env file for better flexibility across different environments.

Changes

• Created src/config/cors.js to manage all CORS logic in one place
• Added .env variable ALLOWED_ORIGINS for dynamic allowed origins
• Applied shared CORS setup for both Express routes and Socket.IO
• Updated server.js to use corsMiddleware() and socketCorsConfig
• Improved maintainability, readability, and environment adaptability

Environment Variables

ALLOWED_ORIGINS=http://localhost:5173,https://guessync.netlify.app

[tusharnain]

@yep-yogesh take a look.