refactor: modernize and streamline authentication and cron update middlewares

[w4lyf]

Refactored JWT authentication middleware:

Used modern ES6+ syntax (arrow functions, destructuring).

Improved error handling and logging.

Simplified logic and added descriptive comments.

Renamed function for clarity (authenticate).

Refactored cron-based booking expiration middleware:

Used Promise.all for concurrent DB updates.

Improved readability and performance.

Wrapped logic in try-catch for better resilience.

Enhanced console logging for clarity.