feat(lotus-sim): wire up signal handler

cmd/lotus-sim/main.go

@@ -1,8 +1,11 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"os"
+	"os/signal"
+	"syscall"
 
 	logging "github.com/ipfs/go-log/v2"
 	"github.com/urfave/cli/v2"
@@ -44,7 +47,11 @@ func main() {
 		},
 	}
 
-	if err := app.Run(os.Args); err != nil {
+	ctx, cancel := signal.NotifyContext(context.Background(),
+		syscall.SIGTERM, syscall.SIGINT, syscall.SIGHUP)
+	defer cancel()
+
+	if err := app.RunContext(ctx, os.Args); err != nil {
 		fmt.Fprintf(os.Stderr, "Error: %s\n", err)
 		os.Exit(1)
 		return