👑[Enhancement] 建议添加一些ipv6的优质DNS，并提高优先级

### 🥰 需求描述(Description)

要求添加ipv6的代理dns，并选择其一设为默认
### 🧐 解决方案(Solution)

代理设置-自定义dns添加一些ipv6，延迟50以下的dns
### 🚑 其他信息(Other Information)

No source file, test, or entry point is named in the issue. Start by locating the proxy settings and custom DNS implementation, then inspect how DNS choices are stored and selected as default. Done means adding suitable IPv6 proxy DNS choices, applying the requested default, and covering the selection behavior; the proposed latency-under-50 criterion still needs clarification.

Written by the indexing model from the issue text.