refactor: 角色添加是否系统角色字段相关逻辑

app/admin/controller/v1/Role.php

@@ -227,6 +227,10 @@ class Role
             return error('请确认要操作对象是否存在');
         }
 
+        if (1 == $role->is_system) {
+            return error('该角色禁止删除');
+        }
+
         if (!$role->delete()) {
             return error('操作失败');
         }

app/common/model/SysRoleBaseModel.php

@@ -21,6 +21,7 @@ class SysRoleBaseModel extends BaseModel
         'pid'        => 'int',
         'name'       => 'string',
         'desc'       => 'string',
+        'is_system'  => 'int',
         'created_at' => 'datetime',
         'updated_at' => 'datetime',
         'deleted_at' => 'datetime',