fix(docs/turn-loop): correct allowedRecipients example name to ruth

The manager's logical name is 'ruth' (MANAGER_AGENT post-#954).
The example used the stale 'manager' placeholder.

docs/turn-loop.md

@@ -488,8 +488,9 @@ ttl_seconds?, to?)`, `answer(id, answer)`.
   message to a prior id for thread rendering. Per-agent
   `hyperhive.allowedRecipients` (default: empty = unrestricted) limits
   which names `send` accepts — useful for sandboxing: set
-  `[ "manager" ]` to restrict a sub-agent to manager-only chatter.
-  The manager is always reachable regardless of the list.
+  `[ "ruth" ]` to restrict a sub-agent to ruth-only chatter
+  (`ruth` is the manager's logical name). `ruth` is always reachable
+  regardless of the list.
 - `recv` — drain inbox. Without `wait_seconds` (or `0`) returns
   immediately. Positive value parks the turn up to that many seconds
   (cap 180) — incoming messages wake instantly. `max` (default 1, cap