Bluesky app fork with some witchin' additions 馃挮 forked from jollywhoppers.com/witchsky.app

Unify build concurrency to one build per platform (#9655) master

Configure concurrency groups so only one iOS build and one Android build can run at a time across all workflows. This prevents manual builds from conflicting with automatic builds triggered by fingerprint changes. Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>