Task 4 rewrote src/db.js and src/jobs/jobRepository.js to use Prisma
instead of the hand-rolled mariadb pool. This updates every remaining
call site (app.js, server.js, worker.js, cleanup.js) and the 5 test
files that still referenced getPool/closePool/pool.query, so the app
and full test suite compile and run against Prisma Client.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>