Add user management

backend/app/repository/user_repository.go

@@ -0,0 +1,17 @@
+package repository
+
+import (
+	"errors"
+	"quay/app/models"
+)
+
+var ErrUserAlreadyExists = errors.New("user already exists")
+
+type UserRepository interface {
+	GetAllUsers() ([]models.User, error)
+	GetUserById(id string) (*models.User, error)
+	GetUserByName(name string) (*models.User, error)
+	CreateUser(user *models.User) error
+	UpdateUser(user *models.User) error
+	DeleteUser(id string) error
+}