No auth

[djrarky]

1. Optional “No‑Auth” mode

When DISABLE_AUTH=true, the application skips all login and permission checks.
The app behaves as if you’re always authenticated and an admin.
This is useful if you rely on external SSO or reverse‑proxy auth and want Nutify to stay open internally.

2. Setup wizard still runs — but the admin step is hidden

If no users exist, the setup wizard still runs so you can configure NUT.
However, the admin user setup step is hidden in the UI when auth is disabled, so you don’t need to manually enter credentials during onboarding.

3. Documentation and compose examples updated

The README and docker-compose example now include:

DISABLE_AUTH=true

SKIP_PERMCHECK=true

Also resolves #71