Add PowWorker to mine Nostr events off the main thread

src/workers.ts

@@ -0,0 +1,9 @@
+import * as Comlink from 'comlink';
+
+import type { PowWorker } from './workers/pow.worker';
+
+const powWorker = Comlink.wrap<typeof PowWorker>(
+  new Worker(new URL('./workers/pow.worker.ts', import.meta.url), { type: 'module' }),
+);
+
+export { powWorker };