De-emphasize "Bluesky" branding

[bnewbold]

This is not a priority thing right now, but would be good to de-emphasize "Bluesky" branding in Ozone.

For example, the login screen says "Bluesky Admin Tools"; it could say "Ozone Moderation Service", or "atproto". We don't need to remove all mention of bluesky, just try to clarify protocol/app distinction, and make it more appropriate for folks using Ozone who have no affiliation with Bluesky PBC, or are using it to moderate non-bsky Lexicons.