feat(gateway): wire safe-point runtime cancellation for agent.cancel

src/backends/native/orchestrator.ts

@@ -304,6 +304,16 @@ export class AgentOrchestrator {
     this._agent.setOnToolUse(callback);
   }
 
+  /** Request cancellation for the current primary-agent operation. */
+  cancel(): void {
+    this._agent.cancel();
+  }
+
+  /** Whether the primary agent currently has an in-flight operation. */
+  isCancellable(): boolean {
+    return this._agent.isCancellable();
+  }
+
   // ── Usage & config accessors ──────────────────────────────────────
 
   /**