feat(bilibili): add feed-detail and enhance feed command

[harveyyue]

Summary

• Add new feed-detail command to view dynamic details (supports exclusive content)
• Enhance feed command to support viewing specific user's dynamics via uid parameter
• Add support for multiple dynamic types: video, article, draw, text, forward
• Add pagination support with pages parameter

[Astro-Han]

Nice expansion of the bilibili adapter. I think the new commands are useful.

A couple of follow-ups, neither feels blocking to me:

feed-detail expects a dynamic id, but feed currently rewrites some rows to the target jump_url for videos and articles. That makes the documented feed -> feed-detail path hard to use for common item types, because the original https://t.bilibili.com/<id> link is no longer in the output. I think it would be safer to keep the dynamic URL as the main url, or add a separate dynamic_id / dynamic_url field.

Also, this PR includes the ke docs and index entry, which looks unrelated to the bilibili change. I would probably split that into a separate PR so this one stays focused.

One more small doc sync item: since feed-detail is user-facing, README.md and README.zh-CN.md should probably list it too.