test(e2e): read the admin JWT from the cookie, not the login body (#1073)

Stable twin of #1071.

Three specs acquire an admin token with `const body = await res.json();
return body.token`. On this branch too the admin login sets the JWT as
the httpOnly `admin_token` cookie and responds with `res.json({ user })`
— verified in auth.js on stable, not assumed from main — so the token is
undefined and each spec fails at its first assertion, before exercising
anything it was written to cover.

Cookie and Authorization: Bearer are interchangeable server-side, so the
helpers read the value back out of the context cookie jar and keep
threading it as a Bearer. Every downstream call is unchanged.

Verification is weaker than the main twin's, deliberately: the three
spec files are byte-identical to the ones measured there (0 passed /
6 failed before, 3 passed / 3 failed after, against a live stack), and
they compile and enumerate on this branch. Standing up a full stable
compose stack to re-measure test-only changes was not worth it — say the
word if you want that done before merge.

The remaining failures are UI staleness, not auth, and are not addressed
here. No CI workflow runs tests/e2e on this branch either, which is why
this rotted unnoticed.

Claude-Session: https://claude.ai/code/session_01Ra4hcsYiKuQLbbRsg6EjAc

Co-authored-by: Paul Nothaft <[email protected]>

tests/e2e/auth-smoke.spec.ts

@@ -18,9 +18,9 @@ async function createEventWithPhotos(page: Page, adminToken?: string, attempt =
       },
     });
     expect(loginResponse.ok()).toBeTruthy();
-    const loginData = await loginResponse.json();
-    token = loginData.token;
-    expect(token).toBeTruthy();
+    const cookies = await page.context().cookies();
+    token = cookies.find((c) => c.name === 'admin_token')?.value;
+    expect(token, 'admin_token cookie missing from the login response').toBeTruthy();
   }
 
   const eventName = `Playwright Smoke ${Date.now()}`;