test(agents): dedupe subagent registry test mocks

src/agents/subagent-registry.mocks.shared.ts

@@ -0,0 +1,15 @@
+import { vi } from "vitest";
+
+const noop = () => {};
+
+vi.mock("../gateway/call.js", () => ({
+  callGateway: vi.fn(async () => ({
+    status: "ok",
+    startedAt: 111,
+    endedAt: 222,
+  })),
+}));
+
+vi.mock("../infra/agent-events.js", () => ({
+  onAgentEvent: vi.fn(() => noop),
+}));