fix(auth-service): 密码登录时对手机号做 E.164 归一化

注册时手机号存储为 +8618926762721，但密码登录用原始输入
18926762721 查库，导致找不到用户。在 login() 中先尝试
Phone.create() 归一化，如果不是合法手机号则作为邮箱使用。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/services/auth-service/src/application/services/auth.service.ts

@@ -113,7 +113,14 @@ export class AuthService {
   /* ── Password Login ── */
 
   async login(dto: LoginDto): Promise<AuthResult> {
-    const user = await this.userRepo.findByPhoneOrEmail(dto.identifier);
+    // Normalize phone numbers to E.164 before lookup (e.g. 18926762721 → +8618926762721)
+    let identifier = dto.identifier;
+    try {
+      identifier = Phone.create(dto.identifier).value;
+    } catch {
+      // Not a valid phone number — treat as email, use as-is
+    }
+    const user = await this.userRepo.findByPhoneOrEmail(identifier);
     if (!user) {
       throw new UnauthorizedException('账号或密码错误');
     }