Eliminate the unused --delete-local option and related code from the
filesystem migration script to prevent accidental local data removal.
Introduce a cleanupClaimedLegacyFsSources utility for removing legacy
filesystem sources after claim, and integrate it into the user claim
flow. Add unit tests to verify the cleanup logic.
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.