feat: add graceful shutdown on SIGINT

mantis/src/core/system.rs

@@ -169,6 +169,9 @@ impl System {
             .map_err(HttpError::BindPortError)?;
 
         axum::serve(listener, app)
+            .with_graceful_shutdown(async {
+                tokio::signal::ctrl_c().await.ok();
+            })
             .await
             .map_err(HttpError::ServerPanic)?;
 
@@ -240,4 +243,4 @@ impl System {
         }
         Ok(())
     }
-}
+}