Eliminate all code, tests, and utilities related to the legacy 'unclaimed' user
scope. All API endpoints, document and audiobook storage, and access logic now
require a valid authenticated userId and only operate on resources owned by that
user. Remove related helper functions, test cases, and conditional flows for
anonymous/unclaimed data. Update types, client APIs, and UI logic to reflect
that only 'user' scope is supported. This simplifies ownership checks and
removes ambiguity around document and audiobook access.
Eliminate all code paths, configuration, and documentation related to running
without authentication. Require AUTH_SECRET and BASE_URL at startup, updating
middleware, server logic, and runtime checks to assume auth is always enabled.
Simplify onboarding, settings, and test helpers to reflect mandatory auth.
Update environment examples, Docker and deployment docs, and CI/test configs.
Remove no-auth-specific UI flows, test cases, and feature toggles.
