feat: Refactor styles and add dotenv and dev mode support

- Updated app.scss and index.scss to use modern Sass @use syntax for global styles.
- Introduced _globals.scss for shared style variables and mixins.
- Added godotenv package to load environment variables from a .env file.
- Implemented isDevelopmentMode function to toggle cookie settings based on the environment.
- Adjusted CORS settings and cookie configurations for development and production modes.

Author: saharsh-agrawal

.env.template

@@ -1,4 +1,5 @@
 JWT_SECRET_KEY=
 OTP_VALIDITY_PERIOD=600
 RESEND_OTP_COOLDOWN=60
-JWT_EXPIRY_DAYS=90
+JWT_EXPIRY_DAYS=90
+DEVELOPMENT_MODE=true

.gitignore

@@ -7,3 +7,5 @@ heimdall
 credentials.json
 token.json
 .env
+
+heimdall.exe