Add graceful shutdown

[Aharshi3614]

Description

Currently, when the server stops (SIGTERM/SIGINT), it abruptly closes connections. This can cause in-flight requests to fail.

Goals

• Close server gracefully on SIGTERM/SIGINT
• Wait for existing requests to complete
• Disconnect database properly

[github-actions]

👋 Welcome back! Thanks for your continued contribution. Your issue/PR is received and waiting for maintainer review.

[github-actions]

The issue highlights the need to implement a graceful shutdown process for the server to address its current behavior of abruptly closing connections during termination signals (SIGTERM/SIGINT). The goals include allowing in-flight requests to complete, properly disconnecting the database, and ensuring a smoother shutdown overall.