feat(jobs): echo worker + CLI bootstrap

Job queue starts only in the CLI gate (not inside createApp), so tests
manage their own queue lifecycle. waitForJob() takes a (name, id) pair
to match pg-boss v10's getJobById signature.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/jobs/workers/echo.js

@@ -0,0 +1,5 @@
+export const NAME = 'echo';
+
+export async function handler(job) {
+  return { pong: job.data?.ping ?? 0 };
+}