The admin-room command stays in #admins' history, so a grant tuwunel
ignores must not be re-sent every five minutes. The controller now
sends `make-user-admin` at most once per operator per process; an
operator still missing from the room on a later pass is logged as
"make-user-admin for an operator failed to take" and left alone until
the controller restarts. The cap lives in the pure `plan()`.
swarm-matrix-client's `user_exists` and `joined_members` read their
responses through pure `profile_verdict` / `joined_verdict`, the shape
`whoami` / `whoami_verdict` already has, with every branch tested: only
M_NOT_FOUND is "no account", and a 403 or a list without `joined` is an
error rather than an answer.
The bridge's handling after authentication moves into `respond()`,
which takes the config and write lock instead of the whole AppState, so
a test can drive ListOperators through the real request path and see
the 403 without an HTTP client or an authelia.
docs/integrations/matrix.md no longer says @swarm is the only homeserver
admin.