feat: basic login

src/users/dto/create-user.dto.ts

@@ -1,4 +1,4 @@
-import { IsNotEmpty, IsUUID } from 'class-validator';
+import { IsNotEmpty, IsOptional, IsUUID, ValidateIf } from 'class-validator';
 
 export class CreateUserDto {
   @IsNotEmpty()
@@ -10,6 +10,9 @@ export class CreateUserDto {
   @IsUUID()
   roleId: string;
 
+  @ValidateIf((o) => {
+    return !!o.superior;
+  })
   @IsUUID()
   superior: string;
 }