A settings namespace is now a kind; each registration is an instance
filed under the caller's nearest named scope (dsh-scope gains
createScope(..., { id }) and scopeIdOf). Instances resolve defaults →
composition base → global user section → scopes.<id>.<ns>. Global writes
fan out to every instance gated on its own resolved value; scoped writes
commit one instance. Revisions are per section so a scope nothing has
registered yet can still be written when the kind exists. describe(),
the controller verbs, and both events take an optional trailing scope.
Presets name their standing scopes preset/<id>; skill-filesystem is the
first consumer, resolving customSkillDirs per scope with live updates.
Yichen Jiang