Betula integration

[danilax86]

• [x] I have tested my changes
• [x] There is no breaking changes
• [x] I really tested my changes and there is no regression
• [ ] Ideally, my commit messages use the same convention as the Go project: https://go.dev/doc/contribute#commit_messages
• [x] I read this document: https://miniflux.app/faq.html#pull-request

Hi! This is the integration for Betula, a bookmarking service. I invite @bouncepaw, an author of Betula, to this PR.

There is a video how integration works.

[bouncepaw]

Hello!

Betula is a bookmark saving software. Out of existing Miniflux integrations, I guess it is the closest to Pinboard, Shaarli and Raindrop; maybe more, I do not know all of the services. You can read more about Betula on its website. It also seems that a significant part of Betula users are also heavy Miniflux users (including me).

I did not take part in the development of this PR and I'm not well-versed with Miniflux's codebase. Betula supports tags, descriptions and titles for every bookmark alongside the URL. Is it possible to do that all in the integration? I don't see a description field in this PR and don't understand where the tags are coming from.

Maybe also inject a miniflux tag for all saved bookmarks?

[bouncepaw]

All checks seem to have passed. Are you interested in this integration?

[fguillot]

You need to rebase your PR because there is a conflict detected.

[danilax86]

@fguillot conflict resolved

[fguillot]

It would be nice if you can update the documentation on the website: https://github.com/miniflux/website/blob/c48b43ba8ea8229d4a26628fcaa5dd31a59bf837/content/docs/_index.md?plain=1#L32

It took me a while to figure out where to get the Betula token.

[bouncepaw]

I will write the docs later.

Danila also contributed a useful button that copies the token, it will go to our next release: https://codeberg.org/bouncepaw/betula/pulls/19#issuecomment-2076728