chore: raise heartbeat ack window

docs/gateway/heartbeat.md

@@ -57,7 +57,7 @@ custom body (sent verbatim).
 - If nothing needs attention, reply with **`HEARTBEAT_OK`**.
 - During heartbeat runs, Clawdbot treats `HEARTBEAT_OK` as an ack when it appears
   at the **start or end** of the reply. The token is stripped and the reply is
-  dropped if the remaining content is **≤ `ackMaxChars`** (default: 30).
+  dropped if the remaining content is **≤ `ackMaxChars`** (default: 300).
 - If `HEARTBEAT_OK` appears in the **middle** of a reply, it is not treated
   specially.
 - For alerts, **do not** include `HEARTBEAT_OK`; return only the alert text.
@@ -78,7 +78,7 @@ and logged; a message that is only `HEARTBEAT_OK` is dropped.
         target: "last",         // last | whatsapp | telegram | discord | slack | signal | imessage | none
         to: "+15551234567",     // optional provider-specific override
         prompt: "Read HEARTBEAT.md if exists. Consider outstanding tasks. Checkup sometimes on your human during (user local) day time.",
-        ackMaxChars: 30          // max chars allowed after HEARTBEAT_OK
+        ackMaxChars: 300         // max chars allowed after HEARTBEAT_OK
       }
     }
   }