XMPP: Post to PubSub

Greetings!

In XMPP, using PubSub(1) (XEP-0060), it is possible to store posts as Atom Syndication(2) entries into XMPP(3).

There are several XMPP extensions that apply it, namely XEP-0227 (4) and XEP-0472 (5) which make node `urn:xmpp:microblog:0` as a common choice to manage news for client accounts (e.g. `blog@koekr.site`), yet a component account (e.g. `pubsub.koekr.site`) may use all of its nodes for this purpose.
```
pubsub.koekr.site/
|
|-- updates/
|-- Sombre
`-- Varied
|-- releases/
`-- events/
pubsub service/
|
|-- node/
|-- item
`-- item
|-- node/
`-- node/
```
A go library that can be utilized would be go-xmpp.

I have made a script that realizes viewing PubSub node items as Atom XML feeds over HTTP.

[XEP-0060: Publish-Subscribe](https://xmpp.org/extensions/xep-0060.html)
[RFC 4287: The Atom Syndication Format](https://www.rfc-editor.org/rfc/rfc4287)
[Atom Over XMPP](https://datatracker.ietf.org/meeting/66/materials/slides-66-atompub-1.pdf)
[XEP-0277: Microblogging over XMPP](https://xmpp.org/extensions/xep-0277.html)
[XEP-0472: Pubsub Social Feed](https://xmpp.org/extensions/xep-0472.html)
[go-xmpp](https://github.com/xmppo/go-xmpp)
[PubSub Over HTTP](https://codeberg.org/poezio/slixmpp/issues/3526)

No repository files, tests, or implementation entry points are identified. Start by reviewing the project structure and the referenced go-xmpp and PubSub specifications, then determine the intended integration and HTTP/Atom feed boundary. Done would require a defined scope and an agreed implementation path for posting or exposing XMPP PubSub content.

Written by the indexing model from the issue text.