feat(admin): add admin endpoint to list user devices with JPush registration IDs

- Add AdminDeviceTokenResponse DTO including push_token (RegistrationID) for push debugging
- Add DeviceTokenToAdminResponse and DeviceTokensToAdminResponse converters
- Inject PushService into AdminUserHandler for retrieving user devices
- Register GET /api/v1/admin/users/:id/devices route for querying target user's device tokens

internal/repository/device_token_repo.go

@@ -18,6 +18,10 @@ type DeviceTokenRepository interface {
 	GetActiveByUserID(userID string) ([]*model.DeviceToken, error)
 	GetByDeviceID(deviceID string) (*model.DeviceToken, error)
 	GetByPushToken(pushToken string) (*model.DeviceToken, error)
+	// DeactivateByPushToken 失效指定 pushToken 的所有记录
+	// 用于处理同设备多账号场景：registration_id 是设备级标识，
+	// 当新账号在同一设备注册时，需失效旧账号对该 pushToken 的关联，避免跨账号误推
+	DeactivateByPushToken(pushToken string) error
 	DeactivateAllExcept(userID int64, deviceID string) error
 	Upsert(token *model.DeviceToken) error
 	UpdateLastUsed(deviceID string) error
@@ -104,6 +108,15 @@ func (r *deviceTokenRepository) GetByPushToken(pushToken string) (*model.DeviceT
 	return &token, nil
 }
 
+// DeactivateByPushToken 失效指定 pushToken 的所有记录
+// registration_id（pushToken）是设备级标识，同一物理设备登录不同账号时 pushToken 不变。
+// 失效旧关联可防止给账号 A 推送时，同设备的账号 B 也收到通知。
+func (r *deviceTokenRepository) DeactivateByPushToken(pushToken string) error {
+	return r.db.Model(&model.DeviceToken{}).
+		Where("push_token = ?", pushToken).
+		Update("is_active", false).Error
+}
+
 // DeactivateAllExcept 登出其他设备（停用除指定设备外的所有设备）
 func (r *deviceTokenRepository) DeactivateAllExcept(userID int64, deviceID string) error {
 	return r.db.Model(&model.DeviceToken{}).