feat: skip auto-review when active CI watcher exists

When the owner registers a CI watcher and completes the turn, the
review loop no longer triggers. The watcher result will be posted
via the reviewer bot, which the owner picks up and acts on, then
the normal review loop resumes.

src/db.ts

@@ -1411,6 +1411,17 @@ export function deleteTask(id: string): void {
   }
 }
 
+export function hasActiveCiWatcherForChat(chatJid: string): boolean {
+  const row = db
+    .prepare(
+      `SELECT 1 FROM scheduled_tasks
+       WHERE chat_jid = ? AND status = 'active' AND prompt LIKE '[BACKGROUND CI WATCH]%'
+       LIMIT 1`,
+    )
+    .get(chatJid);
+  return !!row;
+}
+
 export function getDueTasks(): ScheduledTask[] {
   const now = new Date().toISOString();
   return db