ask_operator tool: non-blocking; operator answer arrives as helper event

new mcp tool on the manager surface that queues a question on the
dashboard and returns the question id immediately. operator submits an
answer via /answer-question/<id>; the dashboard fires
HelperEvent::OperatorAnswered { id, question, answer } into the manager
inbox so the next turn picks it up.

also: fix async-form button stuck on spinner after successful submit
(refreshState skipped re-rendering, so the button was never re-enabled).

hive-c0re/src/broker.rs

@@ -101,8 +101,7 @@ impl Broker {
     /// inbox view on the dashboard. Caller decides what to show.
     pub fn recent_for(&self, recipient: &str, limit: u64) -> Result<Vec<InboxRow>> {
         let conn = self.conn.lock().unwrap();
-        let limit_i =
-            i64::try_from(limit.min(i64::MAX as u64)).unwrap_or(i64::MAX);
+        let limit_i = i64::try_from(limit.min(i64::MAX as u64)).unwrap_or(i64::MAX);
         let mut stmt = conn.prepare(
             "SELECT id, sender, body, sent_at
                FROM messages