feat(companion): expose pending event wait observability

src/companion/runtimeClient.test.ts

@@ -305,11 +305,13 @@ describe('CompanionRuntimeClient', () => {
     const client = new CompanionRuntimeClient({
       url: 'ws://127.0.0.1:1',
     });
+    expect(client.pendingEventWaitCount).toBe(0);
 
     const awaited = client.waitForEvent<{ seq: number }>('agent.stream', {
       timeoutMs: 2000,
       predicate: (data) => data.seq === 2,
     });
+    expect(client.pendingEventWaitCount).toBe(1);
 
     (client as unknown as { handleMessage: (raw: string) => void }).handleMessage(
       JSON.stringify({
@@ -327,6 +329,7 @@ describe('CompanionRuntimeClient', () => {
     );
 
     await expect(awaited).resolves.toEqual({ seq: 2 });
+    expect(client.pendingEventWaitCount).toBe(0);
   });
 
   it('waitForEvent rejects on timeout', async () => {