test: add auth flow integration tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/__tests__/helpers.ts

@@ -0,0 +1,26 @@
+import Fastify from 'fastify';
+import cookie from '@fastify/cookie';
+import rateLimit from '@fastify/rate-limit';
+import authRoutes from '../routes/admin/auth';
+import totpRoutes from '../routes/admin/totp';
+
+export async function buildApp() {
+  const app = Fastify({ logger: false });
+  await app.register(cookie);
+  await app.register(rateLimit, { max: 1000, timeWindow: '1 minute' });
+  await app.register(authRoutes, { prefix: '/api/admin' });
+  await app.register(totpRoutes, { prefix: '/api/admin/totp' });
+  return app;
+}
+
+export function extractCookie(response: any, name: string): string | undefined {
+  const cookies = response.headers['set-cookie'];
+  if (!cookies) return undefined;
+  const arr = Array.isArray(cookies) ? cookies : [cookies];
+  for (const c of arr) {
+    if (c.startsWith(`${name}=`)) {
+      return c.split(';')[0].split('=')[1];
+    }
+  }
+  return undefined;
+}