Make a service shut down cleanly on SIGTERM/SIGINT — stop accepting new work, drain in-flight requests, close DB/queue connections, and exit within the platform's grace period — so deploys and restarts don't drop requests or corrupt state. Use when the user says "add graceful shutdown", "handle SIGTERM", "drain connections on shutdown", "stop dropping requests during deploys", "close connections cleanly on exit", or "my app is killed mid-request".
