feat: scaffold worker application shell

Adds apps/worker with TypeScript config, BullMQ/ioredis dependencies,
pino logger bootstrap, and a smoke test. Queue consumers wired in later phases.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/worker/src/main.test.ts

@@ -0,0 +1,7 @@
+describe('worker bootstrap', () => {
+  it('exports a bootstrap function', async () => {
+    // Dynamic import so main.ts side-effects don't auto-run in tests
+    const mod = await import('./main');
+    expect(mod).toBeDefined();
+  });
+});