Guards against regressions where the session cookie is set but
the backend rejects it — a URL redirect alone is not enough.
Refs #48
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
The logout action was moved into a user avatar dropdown in the nav.
The E2E test was clicking the now-hidden button directly.
Refs #35
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>