add:gracefull shutdown context based

[sahilchauhan123]

Implemented Graceful Shutdown System

This implementation provides a complete graceful shutdown mechanism that:

1. Listens for OS signals:

   • SIGTERM
   • SIGINT

2. Triggers a shutdown sequence with a configurable timeout.
   This ensures all cleanup operations either complete within the allowed time
   or the shutdown is forced.

3. Stops accepting new HTTP requests while allowing in-flight requests to finish.

4. Cleans up application resources in order, including:

   • database connections
   • caches
   • file handles
   • background workers

5. Returns proper UNIX exit codes based on the received signal:

   • 130 → SIGINT
   • 143 → SIGTERM
     This is useful for Docker, Kubernetes, and CI/CD systems.

Cleanup Registration

The shutdown Register supports both types of cleanup functions:

func() error
func(context.Context) error

Both styles are normalized internally so components can choose either simple
or context-aware cleanup logic without changing the shutdown workflow.

All the things are fully tested