refactor: see details below

- Fix emailing.
- Updated manage.sh to enhance command handling and service management for backend and frontend.
- Introduced utility functions for better code organization and readability.
- Added support for checking Node.js version and ensuring the virtual environment is set up.
- Implemented improved logging with color-coded output for better visibility.
- Created a new nginx.conf.example file for easy Nginx configuration setup for the application.

frontend/vite.config.js

@@ -13,6 +13,7 @@ export default defineConfig({
   },
 
   server: {
+    host: '0.0.0.0',  // Listen on all network interfaces for LAN access
     port: 3000,
     proxy: {
       '/api': {