Introduce the framed guest_channel_transport with shared deadlines and
std::jthread ownership, metadata-only retired-schema quarantine with
fail-closed integrity, stateless frozen-catalog validators with
capability pinned to zero, and the generic local-service proxy with
descriptor-pinned endpoints, alias-only guest sockets, audit-gated
delivery, and a Linux managed runtime capability derived only from a
registry-bound operational factory. Sage vocabulary is confined to
src/adapters/sage.
