tr -cs 'a-z0-9_-' '-' only allowed lowercase letters, so any uppercase
leading character (e.g. "Bob") got converted to a dash and then stripped
by the paired leading-dash sed, silently truncating the username. Widened
to a-zA-Z0-9_- in both add_authelia_user() and _authelia_scope_access().
Also extends the "Manage an existing user" menu (still numbered-selection
throughout) with:
- option 6: toggle a user's membership in any existing "<service>-only"
scoped-access group, picked by number, via two new helpers
(_authelia_list_scoped_groups, and re-resolving the user's line range
before each toggle since a prior toggle in the same pass shifts it)
- option 7: delete a user outright (_authelia_delete_user_block), with confirmation
Verified against a synthetic users.yml (add/remove toggling across
multiple groups, block deletion, uppercase-username round-trip) before
touching the live file.