Vectors: extra-slot-store.cc gains the unit-arm record (tests.slot_unit); extra-slot-consent.cc
(records under tests.union_surface.wide) and slot-outcomes.msgpack are new. The consent reader
(SurfaceDeclaring, listing the wide id compatible) and UnitDoc move into UnionParityVectorTests;
the in-test consent store construction, Relabel and AppendRootSlot go. Red against 115bc0a2:
9 tests (spec cultlib-gaps:cut_spec:cut-slot-tolerance.r5).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>