change user type from int to uuid string

api/user.go

@@ -1,7 +1,15 @@
 package api
 
+import (
+	"github.com/google/uuid"
+)
+
+func newUserID() string {
+	return "user_" + uuid.New().String()
+}
+
 type User struct {
-	ID   int64  `json:"id"`
+	ID   string `json:"id"`
 	Name string `json:"name"`
 }