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/index.js

@@ -0,0 +1,10 @@
+import * as queue from './queue.js';
+import * as echo from './workers/echo.js';
+
+const WORKERS = [echo];
+
+export async function registerWorkers() {
+  for (const w of WORKERS) {
+    await queue.subscribe(w.NAME, w.handler, w.opts || {});
+  }
+}

lib/jobs/workers/echo.js

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