Add `hivectl gateway {create-user,delete-user,list-users}` subcommands for
managing htpasswd files used by gateway Basic auth. Pure Rust bcrypt
(cost 12, $2y$ prefix nginx accepts). No external htpasswd binary required.
Also fix the NixOS module assertion: `cfg.auth ? htpasswdFile` is always
true in the module system (declared options always exist as keys); switch
to `nullOr path; default = null` + `!= null` check so the assertion
actually fires with a useful error when enable=true but no file is set.
Guard bind-mount and nginx config against null to prevent eval errors.
Update docs/gateway.md to show hivectl commands instead of raw htpasswd.
questions pane now shows both operator-targeted threads
(target IS NULL) and agent-to-agent threads (target = some
agent). filter chips above the list: all / @operator / @peer /
per-participant. peer rows get a mauve left rule + a 0V3RR1D3
button that POSTs the same /answer-question endpoint
(OperatorQuestions::answer already permits the operator as
answerer on any target).
wire changes: OperatorQuestions gains pending_all +
recent_answered_all; QuestionAdded + QuestionResolved events
carry target: Option<String>; emit sites drop their
target.is_none() guard. answered-history rows show the
answerer prefix so override answers are auditable at a glance.
