acl.py kept its own copy of the role constants, so an installation could
pair the new numbering with a core that still derives is_admin from the
0x02 bit. That combination announces a room server's READ_WRITE clients
(role 2) as admins on the login reply's is_admin byte — silently, and
exactly where this change is meant to make the two bytes agree. The
dependency is a mutable openhop_core@dev, so nothing prevented it.
Import the roles and acl_is_admin/acl_role from openhop_core instead of
duplicating them, and raise an actionable ImportError when they are
absent: refusing to start beats misannouncing a client's privileges. The
drift test no longer skips on an old core, so CI reports the mismatch
rather than hiding it.