feat: add reusable jobqueue library

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/SseSerializer.test.ts

@@ -0,0 +1,25 @@
+import { SseSerializer } from '../src/index.js';
+
+describe('SseSerializer', () => {
+  it('formats SSE events', () => {
+    const serializer = new SseSerializer();
+    const event = serializer.event('job:completed', {
+      type: 'job:completed',
+      jobId: 'job-1',
+      timestamp: '2026-01-01T00:00:00.000Z',
+    });
+
+    expect(event).toContain('event: job:completed');
+    expect(event).toContain('"jobId":"job-1"');
+    expect(event.endsWith('\n\n')).toBe(true);
+  });
+
+  it('returns SSE headers', () => {
+    expect(SseSerializer.headers()).toEqual({
+      'Content-Type': 'text/event-stream',
+      'Cache-Control': 'no-cache',
+      Connection: 'keep-alive',
+      'X-Accel-Buffering': 'no',
+    });
+  });
+});