Part of CLI module work (fastapi-oidc-op-9lb.1). The test verifies that /register/{token} handles users already created by initial-admin.
Implement Phase 4 auth routes: password login/logout, WebAuthn registration and authentication, magic link registration, and credential management pages with HTMX. Includes session middleware, Jinja2 templates, vendored HTMX, and last-credential guardrails. 120 tests passing.