Smoke tests for the Jalon 0 'Tests d'integration smoke par BC'
item need a small helper to:
- issue a GET on an in-memory test server (HttpClient built by
TestWebApplicationFactory<Program>);
- assert that the response is 2xx (page served), 3xx (redirect
to login) or 401/403 (anonymous rejected). Anything else —
404 route missing, 5xx server crash, connection refused —
fails the test.
This commit only introduces the base class. Subsequent commits
add the per-BC smoke tests (Account, Blog, etc.).
