/classes lists upcoming sessions for any member with spots-left,
sign-up / join-waitlist and cancel (waitlist auto-promotes on cancel via
the action). Holders of classes.instruct/manage get an inline attendees
panel to mark attendance and complete the session; completion issues the
class's certification through the normal grant path and the UI reports
when certificates were skipped (no certifications.grant). Sidebar gets a
member-visible "Classes" link.
/classes/manage (guarded by classes.manage) lists classes with inline
create/edit, archive/restore, delete (refused once sessions exist), an
optional grants-certification picker and a generic payment link, plus
per-class session scheduling with cancel/delete. Sidebar gets a "Manage
classes" link in the Admin block. The member-facing catalog/signup is
the next phase.