Cannot Verify Selfhosted ATProtocol (Bluesky) Accounts to Gravtar

# Bug Report

## Description / Observed Behavior
Attempted to add Bluesky account under "Verified Accounts" section of Gravatar, but was unable to do so. My account "sharpiepls.com" is no longer hosted on the "bsky.app" PDS and has moved to "blacksky.app" PDS. This tends to cause issues to applications that are only looking to official Bluesky servers for authorization.

Oauth structure in the Gravatar section does not allow changing hosting providers to the specific server where the ATProto account may be hosted.

## Expected Behavior

Adding my ATProto account to the verified accounts.

How did you expect the component or service to behave here?

## Repro Steps / Code Example

## Your Environment

- Component/Service Name and Version: [e.g. library-name v1.0.0]
- Platform: Firefox
- Operating System / Browser: Windows 11

## Additional Information

Any other information about the problem here.

Start by reproducing the Verified Accounts OAuth flow in Firefox on Windows 11, using the supplied screenshots and the self-hosted sharpiepls.com account as context. Trace how the flow selects an ATProtocol hosting provider; done means an account hosted on a non-bsky.app PDS can be added to verified accounts.

Written by the indexing model from the issue text.