feat(migrate): CLI dispatch + verify

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

migrate/verify.js

@@ -0,0 +1,10 @@
+import { pool } from '../lib/db/pool.js';
+
+// Per-source/type migrated counts (from migration_map) + Karakeep refs (which use
+// upsertByExternal, not migration_map). Used to audit completeness before cutover.
+export async function verify() {
+  const { rows: map } = await pool.query(
+    `SELECT source, entity_type, count(*)::int n FROM migration_map GROUP BY source, entity_type ORDER BY source, entity_type`);
+  const { rows: [{ n: bookmarks }] } = await pool.query(`SELECT count(*)::int n FROM refs WHERE source_kind='karakeep'`);
+  return { map, bookmarks };
+}