feat(user): add identity and verification status to user DTOs

Add Identity and VerificationStatus fields to UserResponse, UserSelfResponse,
and UserDetailResponse. Only expose identity information when verification
status is approved to protect privacy of pending/rejected applicants.

internal/dto/dto.go

@@ -24,6 +24,9 @@ type UserResponse struct {
 	IsFollowing    bool   `json:"is_following"`
 	IsFollowingMe  bool   `json:"is_following_me"`
 	CreatedAt      string `json:"created_at"`
+	// 认证信息
+	Identity           model.UserIdentity       `json:"identity,omitempty"`
+	VerificationStatus model.VerificationStatus `json:"verification_status,omitempty"`
 }
 
 // UserSelfResponse 用户自身信息响应（包含敏感信息，仅本人可见）
@@ -46,6 +49,9 @@ type UserSelfResponse struct {
 	CreatedAt      string  `json:"created_at"`
 	// 隐私设置
 	PrivacySettings *PrivacySettingsResponse `json:"privacy_settings,omitempty"`
+	// 认证信息
+	Identity           model.UserIdentity       `json:"identity,omitempty"`
+	VerificationStatus model.VerificationStatus `json:"verification_status,omitempty"`
 }
 
 // UserDetailResponse 用户详情响应（仅本人可见，包含敏感信息）
@@ -70,6 +76,9 @@ type UserDetailResponse struct {
 	CreatedAt      string  `json:"created_at"`
 	// 隐私设置
 	PrivacySettings *PrivacySettingsResponse `json:"privacy_settings,omitempty"`
+	// 认证信息
+	Identity           model.UserIdentity       `json:"identity,omitempty"`
+	VerificationStatus model.VerificationStatus `json:"verification_status,omitempty"`
 }
 
 // ==================== Admin User DTOs ====================