resolvePds

Resolves a DID to the URL of the PDS hosting it, by fetching the DID document and reading its #atproto_pds service entry.

Public because callers routinely have a DID already — searchActorsTypeahead and getProfile both return one — and want only this one hop. resolve would work but runs the whole chain (handle → DID → PDS → auth server → metadata), which is four extra round trips for an answer this method gets in one, and is far too heavy to run per row of a list.

Handles did:plc (via plc.directory) and did:web (via the host's /.well-known/did.json). Throws OAuthDiscoveryException for an unsupported DID method, an unreachable or malformed document, or a document with no PDS service entry.