Download and cache profile icons/images locally

[andrewgodwin]

We should probably do this for at least these images just to lessen the load on other servers. We can stash them in the same fields we use for locally uploaded images.

We should also think about how to expire and remove these after a certain amount of time where they've not been used.

[manfre]

There should be a "Needs more JPEG" setting to aggressively downsample or a settable threshold where we let the host server deal with images that are too bloated to justify processing or caching.

[preeefix]

Mastodon has a timeout feature that keeps the retrieved images/content for x days.

[kromonos]

Another option would be making usage of proxing software like morty, like searx is doing. Caching of these content could be done via nginx or apache cache modules.

[andrewgodwin]

I think our general approach might be, for remote images at least and maybe for profile pics, to just use a proxy model - build it into Takahē by default, but have it separable enough it can be pointed and run elsewhere.