Narrow OAuth scope and switch to Bluesky intent/compose
Replace API-based Bluesky posting with bsky.app/intent/compose links,
removing the need for app.bsky.feed.post write access. Drop the blanket
transition:generic OAuth scope in favor of a custom permission set
(blue.checkmate.authFullAccess) scoped to game and challenge records.
Add logo_uri to client metadata for branded consent screen.