fix: bound signal/imessage transport readiness waits

Co-authored-by: Szpadel <1857251+Szpadel@users.noreply.github.com>

src/imessage/monitor.updates-last-route-chat-id-direct-messages.test.ts

@@ -54,6 +54,10 @@ vi.mock("./client.js", () => ({
   }),
 }));
 
+vi.mock("./probe.js", () => ({
+  probeIMessage: vi.fn(async () => ({ ok: true })),
+}));
+
 const flush = () => new Promise((resolve) => setTimeout(resolve, 0));
 
 async function waitForSubscribe() {