feat: add reusable jobqueue library

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

tests/RetentionScheduler.test.ts

@@ -0,0 +1,28 @@
+import { RetentionScheduler } from '../src/index.js';
+
+describe('RetentionScheduler', () => {
+  it('runs stale and delete handlers', async () => {
+    const calls: string[] = [];
+    const scheduler = new RetentionScheduler(
+      {
+        staleAfterMs: 1_000,
+        deleteAfterMs: 2_000,
+      },
+      {
+        markStale: async () => {
+          calls.push('stale');
+          return [];
+        },
+        deleteStale: async () => {
+          calls.push('delete');
+          return [];
+        },
+      },
+    );
+
+    await scheduler.runCycle();
+    scheduler.stop();
+
+    expect(calls).toEqual(['stale', 'delete']);
+  });
+});