[hw-1] implement cart service

cart/cmd/server/main.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"os"
+
+	"route256/cart/internal/app"
+)
+
+func main() {
+	srv, err := app.NewApp(os.Getenv("CONFIG_FILE"))
+	if err != nil {
+		panic(err)
+	}
+
+	if err := srv.ListenAndServe(); err != nil {
+		panic(err)
+	}
+}