fix(user-service): add class-validator decorators to auth DTOs

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/services/user-service/src/auth/auth.controller.ts

@@ -6,22 +6,34 @@ import {
   HttpCode,
   HttpStatus,
 } from '@nestjs/common';
+import { IsString, IsNotEmpty, IsOptional } from 'class-validator';
 import { AuthService } from './auth.service';
 
 class CreateAnonymousDto {
-  fingerprint: string;
+  @IsOptional()
+  @IsString()
+  fingerprint?: string;
 }
 
 class SendCodeDto {
+  @IsNotEmpty()
+  @IsString()
   phone: string;
 }
 
 class VerifyCodeDto {
+  @IsNotEmpty()
+  @IsString()
   phone: string;
+
+  @IsNotEmpty()
+  @IsString()
   code: string;
 }
 
 class RefreshTokenDto {
+  @IsNotEmpty()
+  @IsString()
   token: string;
 }