- dev/migrations/001-innodb.sql: convert pqs_queue + pqs_mission to InnoDB.
- includes/queue.php: pqs_enqueue_player() seats a player in the next open
mission (creating one if needed), serialized with GET_LOCK and wrapped in a
transaction; capacity judged by real COUNT(*), numplayers rewritten from it
so the counter self-heals and can't drift.
- callsign.php: normal registration path now calls pqs_enqueue_player instead
of the non-atomic read-check-insert.
Verified on the local stack: 140 concurrent registrations -> 24 missions,
zero overfill, zero counter drift.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
