chore: add documentation comments and stylecop rules

src/Application/TakeoutSaaS.Application/Identity/Handlers/AssignUserRolesCommandHandler.cs

@@ -15,9 +15,14 @@ public sealed class AssignUserRolesCommandHandler(
 {
     public async Task<bool> Handle(AssignUserRolesCommand request, CancellationToken cancellationToken)
     {
+        // 1. 获取租户上下文
         var tenantId = tenantProvider.GetCurrentTenantId();
+
+        // 2. 覆盖式绑定角色
         await userRoleRepository.ReplaceUserRolesAsync(tenantId, request.UserId, request.RoleIds, cancellationToken);
         await userRoleRepository.SaveChangesAsync(cancellationToken);
+
+        // 3. 返回执行结果
         return true;
     }
 }