- Route group (app) holds AuthProvider + Sidebar, so /login and /setup
render without app chrome and never mount the provider.
- AuthProvider drops the removed auth_enabled flag and exposes
{user, org, isAdmin}.
- New login page (password + SSO), first-run setup page, and org settings
page with a members table and the OIDC provider form.
- Settings page and the Organization nav entry are gated on role, since
/api/settings now 403s for members.
- GET /api/org/oidc gains client_secret_set so the UI can show whether a
secret is stored; the secret itself is still never serialized, and an
empty submitted value still means "keep the stored one".
- Fix logout: the sidebar linked to /auth/logout with a GET, but the route
is POST-only, so logout was 404ing.