fn resolve_identifier(state: &AppState, identifier: &str) -> Option<String>Expand description
Resolves identifier — a handle or a DID — to an account DID this
deployment hosts.
What POST /oauth/par resolves a login_hint with: resolve_repo
under another name, kept separate because a sign-in failure and a
repository lookup failure want different error shapes, and folding them
into one function would make one of the two callers wrong.