添加RSSHub镜像功能

[LAD021]

Clear and concise description of the problem

经常会有RSSHub站点失灵的情况，有可能主站点遭遇反爬，有可能自建站点不再维护。 似乎Follow会推荐他人的订阅，此时会暴露他人的自建站点，用户默认跟随订阅后（可能建站者仅想自用）会对站点造成流量压力（希望引导用户用RSSHub格式订阅）

Suggested solution

已经可以选择订阅方式为RSSHub，但在订阅后无法换源 RSS订阅可以根据配置换源（默认，某个网站，某个订阅这样），这样也方便统计真实的public订阅数目

Alternative

No response

Additional context

No response

Validations

• [X] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[linear[bot]]

FOL-119 添加RSSHub镜像功能

[tangbl2000]

有邀请码吗

[follow-reviewer-bot[bot]]

This issue has been automatically marked as stale. If this issue is still affecting you, please leave any comment (for example, "bump"), and we'll keep it open. If you have any new additional information—in particular, if this is still reproducible in the latest version of Follow or in the beta—please include it with your comment!