Fediverse widget and bot

### Your use case

#### What would you like to do?
Embed, as a widget, a fediverse timeline, a specific account timeline, a local timeline or a federated timline.
And get a bot publishing within the room what a Fediverse account publish.
By Fediverse, I mean Mastodon, Pixelfed etc...
#### Why would you like to do it?
The widget: to be able to follow a specific timeline within a specific room and be able to comment with others.
The bot: to get publication of a fediverse account within the room and be able to start thread on a publication to comment it.
#### How would you like to achieve it?
Widget and bot

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

No files, tests, or entry points are named. Start by clarifying which Element client should provide the widget and bot, and the intended Mastodon/Pixelfed integration scope. Define acceptance criteria for embedded timelines, room comments, account publications, and discussion threads before implementation.

Written by the indexing model from the issue text.