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.ts

@@ -0,0 +1,14 @@
+import { createLogger } from '@tower/logger';
+
+const logger = createLogger('tower-worker');
+
+async function bootstrap() {
+  logger.info('Tower worker starting...');
+  // Queue consumers will be registered here in later phases
+  logger.info('Tower worker ready');
+}
+
+bootstrap().catch((err) => {
+  console.error('Worker failed to start', err);
+  process.exit(1);
+});