gateway: prevent stale web UI assets on localhost

src/gateway/server.test.ts

@@ -295,7 +295,7 @@ describe('GatewayServer integration', () => {
     const res = await fetch(`http://127.0.0.1:${TEST_PORT}/`);
     expect(res.status).toBe(200);
     expect(res.headers.get('content-type')).toBe('text/html');
-    expect(res.headers.get('cache-control')).toBe('no-cache');
+    expect(res.headers.get('cache-control')).toBe('no-store');
     const body = await res.text();
     expect(body).toContain('Flynn');
   });
@@ -307,6 +307,7 @@ describe('GatewayServer integration', () => {
     const res = await fetch(`http://127.0.0.1:${TEST_PORT}/style.css`);
     expect(res.status).toBe(200);
     expect(res.headers.get('content-type')).toBe('text/css');
+    expect(res.headers.get('cache-control')).toBe('no-store');
   });
 
   it('serves sw.js with no-store cache policy', async () => {