fix: trigger agentStatusChanged hook and heartbeat even when framework yields no message

memeloopTaskAgentWorkerHandler yields { state } without a message field (worker-side
bindWorkerConversation handles message materialization). The old code gated hook dispatch
and heartbeat startup inside if (lastResult?.message), so they were never triggered for
memeloop agents. Extract hook + heartbeat into if (lastResult) so they run regardless of
whether the framework attached a message to the terminal yield.

src/services/agentInstance/index.ts

@@ -997,8 +997,12 @@ export class AgentInstanceService implements IAgentInstanceService {
               }
             });
           }
+        }
 
-          // Trigger agentStatusChanged hook with actual terminal state (completed, input-required, etc.)
+        if (lastResult) {
+          // Trigger agentStatusChanged hook with actual terminal state (completed, input-required, etc.).
+          // This must run even when the framework yields no message (e.g. memeloopTaskAgentWorkerHandler
+          // yields { state } without a message; worker-side updates handle message materialization).
           const terminalState = (lastResult.state ?? 'completed') as 'working' | 'completed' | 'failed' | 'canceled' | 'input-required';
           await frameworkHooks.agentStatusChanged.promise({
             agentFrameworkContext: frameworkContext,