Delete unused registry members (ProfileConnectionRegistry.insertIfAbsent /
removeAllForProfile, ProfileRegistry.reorder, ProfilesView.countFor,
ConnectionRegistry.getDefault) and their orphan tests, refreshing the stale
docs that named removeAllForProfile as the profile-delete cleanup path.
Repair the "one default per profile" join-row invariant: the connectionId FK
cascade (foreign_keys=ON) silently drops a profile's default row while its
other rows survive, leaving it defaultless. Add promoteMissingDefaults, share
a deterministic re-promotion helper with remove(), and re-promote in
removeAllForConnection.
edde746