Manually refactor multi-line conn = post/put(conn, ...) patterns
across user_session, user_settings, and user_registration controller
tests. Rename shadowed conn to response using pipeline operator.
Also add plans/multi-line-conn-refactoring.md spec for future
Elixir-based tooling to handle these patterns automatically.
- LiveView-based email/password auth via mix phx.gen.auth
- Auth links removed from public navigation (direct URL access only)
- Accounts context with User schema and token management
