Allow opening multiple album selection as collection

[deckerst]

Discussed in #1012

^{Originally posted by imsodin May 7, 2024}
I searched quite a bit for this in the app or here on github, but couldn't find anything: Can I display/search for pics from multiple albums?

I can select multiple tags one by one on the search page, though that ANDs. I can't do the same for albums, possibly because ANDing makes no sense there.

Long pressing doesn't give me any options towards that (though I found the "filter out" option there, pretty well hidden).

On the album page I can select multiple albums, and even display them on a map or on the slideshow, but not the collection/as thumbnails.

What I want to do: I have a dir/album with my own camera images, and one with ones synced from my partners phone. We are traveling together and I'd like to view and tag them from a single timeline. I can sort of achieve that by filtering out albums that currently introduce new pics to the global timeline, but that's cumbersome and backwards. By the way excluding multiple albums works :)

And side-questions: The only docs are the wiki, right? I was thinning whether done of my confusions and discoveries might be worth contributing as docs, but don't see how/where.