feat(vela): retire mocked.turn.trigger from shared contract

apps/vela-gateway/test/websocket-session.test.js

@@ -256,6 +256,15 @@ test('http routes stay available and preserve the root response contract', async
 	}
 });
 
+test('shared protocol only exposes currently supported client event types', () => {
+	assert.deepEqual(CLIENT_EVENT_TYPES, [
+		'session.start',
+		'input_audio.append',
+		'input_audio.commit',
+		'response.cancel'
+	]);
+});
+
 test('websocket connect creates and cleans up an ephemeral session', async () => {
 	const server = await startServer();