The dev stack shares one stack.env across all services via env_file, so
BookStack inherited Plane's DATABASE_URL (postgresql://...@postgres_plane).
Laravel prioritizes DATABASE_URL over the individual DB_* vars, so BookStack
connected to Plane's Postgres and 500'd with "could not find driver" (the
LSIO image ships pdo_mysql, not pdo_pgsql). Pin DATABASE_URL to BookStack's
own MariaDB DSN in its environment block.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
