add category insert

@@ -0,0 +32,4 @@
+	query := `INSERT INTO categories (name, user_id, favorite, monthly_limit) VALUES (@name, @user_id, @favorite, @monthly_limit)`
+	args := pgx.NamedArgs{
+		"name":          category.Name,
+		"user_id":       1,

@@ -0,0 +29,4 @@
+}
+
+func (s *CategoryService) AddCategory(ctx context.Context, category *CategoryEntity) (*CategoryEntity, error) {
+	query := `INSERT INTO categories (name, user_id, favorite, monthly_limit) VALUES (@name, @user_id, @favorite, @monthly_limit)`