feat: add Go backend compatibility service scaffold

go-backend/cmd/paneld/main.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"go-backend/internal/app"
+	"go-backend/internal/config"
+)
+
+func main() {
+	cfg := config.FromEnv()
+	if cfg.JWTSecret == "" {
+		log.Println("warning: JWT_SECRET is empty")
+	}
+
+	a, err := app.New(cfg)
+	if err != nil {
+		log.Fatalf("failed to create app: %v", err)
+	}
+
+	errCh := make(chan error, 1)
+	go func() {
+		errCh <- a.Run()
+	}()
+
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+
+	select {
+	case sig := <-sigCh:
+		log.Printf("received signal %s, shutting down", sig)
+	case runErr := <-errCh:
+		if runErr != nil && !errors.Is(runErr, http.ErrServerClosed) {
+			log.Fatalf("server stopped unexpectedly: %v", runErr)
+		}
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	if err := a.Shutdown(ctx); err != nil {
+		log.Fatalf("shutdown failed: %v", err)
+	}
+}