Bluesky custom PDS support

Logging into Bluesky accounts that are hosted on custom PDSs (Personal Data Servers) don't work - it seems to be hardcoded to *.bsky.social PDSs (not handles, but accounts hosted on these servers that Bluesky runs). That's the default so many older apps with the Bluesky API hardcoded to that, but self-hosted users are unable to connect with Typefully.

Should be fairly easy to add with automatically resolving the correct PDS URL, or typing in the PDS URL manually for auth

Thanks!