👑[Enhancement] 手机版支持扫码登录功能

### 🥰 需求描述(Description)

手机版Steam++在导入令牌之后，可以像Steam APP那样扫码登录Steam账号。

### 🧐 解决方案(Solution)

通过手机版watt toolkit，可以支持保存多个账户信息后扫码登录指定的账户。

### 🚑 其他信息(Other Information)

不知道这样新功能需求需要捐助多少。

Start by reviewing the mobile token-import and Steam login flows described in the issue, including how multiple accounts are saved and selected. The work is done when the mobile app can scan a Steam-style QR code and log in with the selected imported account; the issue does not name files or tests.

Written by the indexing model from the issue text.