fix(stats): report complete vocabulary totals and new-word history (#202)

src/core/services/immersion-tracker/lexical-rollup-worker-thread.ts

@@ -0,0 +1,11 @@
+import { parentPort, workerData } from 'node:worker_threads';
+import { executeLexicalRollupBackfillTask } from './lexical-rollup-worker';
+
+if (!parentPort) throw new Error('lexical rollup worker missing parent port');
+
+try {
+  executeLexicalRollupBackfillTask((workerData as { dbPath: string }).dbPath);
+  parentPort.postMessage({ ok: true });
+} catch (error) {
+  parentPort.postMessage({ error: error instanceof Error ? error.message : String(error) });
+}