Add ListenBrainz endpoints and types
Implement /1/submit-listens with Token auth, validate body via zod, and
asynchronously match tracks then publish scrobbles for 'single' listens.
Add /1/validate-token and several stub ListenBrainz-compatible routes.
Add Listenbrainz zod schemas and TypeScript types. Use handle from
getDidAndHandle for token validation.