## ADDED Requirements

### Requirement: Device Estimated Final Expiry Display

The device management list integration SHALL preserve and display the five backend device-level estimated final package expiry fields `estimated_final_expires_at`, `days_until_final_expiry`, `expiry_estimate_status`, `expiry_estimate_status_name`, and `is_expiring` returned in `data.items[]` by `GET /api/admin/devices`. The status SHALL be one of `exact`, `waiting_activation`, `none`, or `invalid_data`; non-`exact` records SHALL have `estimated_final_expires_at=null` and `days_until_final_expiry=null`. The frontend SHALL NOT traverse bound cards or calculate package continuation dates. This requirement applies only to the admin device list.

#### Scenario: Display exact device final expiry estimate

- **GIVEN** 设备列表接口返回 `expiry_estimate_status=exact` and `estimated_final_expires_at`
- **WHEN** 页面渲染设备列表行
- **THEN** 页面 MUST display a column labeled `预计套餐到期时间`
- **AND** 该列 MUST format and display `estimated_final_expires_at`

#### Scenario: Display activation-pending device final expiry

- **GIVEN** 设备列表接口返回 `expiry_estimate_status=waiting_activation`
- **WHEN** 页面渲染设备列表行
- **THEN** `预计套餐到期时间` MUST display `待激活后起算`
- **AND** 页面 MUST NOT traverse bound cards or display a fabricated date

#### Scenario: Display device estimate status names for non-exact states

- **GIVEN** 设备列表接口返回 `expiry_estimate_status=none` 或 `expiry_estimate_status=invalid_data`
- **WHEN** 页面渲染设备列表行
- **THEN** `none` MUST display a stable empty placeholder
- **AND** `invalid_data` MUST display `数据异常`
- **AND** 页面 MUST use the status enum to choose the display rule

#### Scenario: Preserve null fields for non-exact device estimates

- **GIVEN** 设备列表接口返回 `expiry_estimate_status=none` 或 `expiry_estimate_status=invalid_data`
- **THEN** `estimated_final_expires_at` MUST be `null`
- **AND** `days_until_final_expiry` MUST be `null`
- **AND** 页面 MUST NOT derive either field from绑定卡或套餐数据

#### Scenario: Highlight expiring device without reordering

- **GIVEN** 设备列表接口返回 `is_expiring=true` and `days_until_final_expiry`
- **WHEN** 页面渲染该设备的预计套餐到期时间
- **THEN** 页面 MUST apply the expiring visual treatment based on the backend fields
- **AND** 页面 MUST NOT change the ordinary device list sort order because of `is_expiring`

#### Scenario: Display no-package device placeholder

- **GIVEN** 设备列表记录没有可预计的最终到期时间
- **WHEN** 页面渲染预计套餐到期时间列
- **THEN** 页面 MUST display a stable placeholder
- **AND** 页面 MUST NOT use an individual package expiry as a substitute

#### Scenario: Preserve device status name without using it for business calculation

- **WHEN** 设备列表接口返回 `expiry_estimate_status_name`
- **THEN** 前端类型 MUST preserve the field
- **AND** 页面 MUST NOT calculate or replace the backend status name
