When the token file is deleted but the homeserver account still exists,
register_user returns M_USER_IN_USE (HTTP 400) and the provisioning
sweep hard-fails, leaving the agent without a working matrix token.
Fix: persist the random password to matrix-password alongside the
access token on first registration. On subsequent attempts where
M_USER_IN_USE is returned, fall back to login_user (m.login.password)
using the stored password. If both files are gone, the error message
guides the operator to `hivectl matrix create-user <name> --password`.
e3b4d38565