fix(v2): await handleRecurrence so the DB isn't closed mid-flight

sweepSession called handleRecurrence without await, then synchronously
closed inDb in its finally block. handleRecurrence is async because it
does a dynamic `import('cron-parser')` before the first DB write; that
import resolved after the finally had already run, so insertRecurrence
hit a closed handle and threw "The database connection is not open".

Net effect: every recurring task was correctly marked completed by
syncProcessingAcks, but its next occurrence never got scheduled.
Single-word fix — `await`.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/host-sweep.ts

@@ -101,7 +101,7 @@ async function sweepSession(session: Session): Promise<void> {
     }
 
     // 4. Handle recurrence for completed messages
-    handleRecurrence(inDb, session);
+    await handleRecurrence(inDb, session);
   } finally {
     inDb.close();
     outDb?.close();