A.2.6:8.2 - Time selector Γ_time

When membership depends on time, the scope predicate and target slice name an exact gammaTime point, interval, or policy and state which boundary changes a slice from member to non-member or back. Implicit “latest” is forbidden. A time-independent predicate need not inspect gammaTime. Keep every selector already declared in the slice schema; do not invent a time selector merely to complete a new declaration. Evidence freshness remains a separate R-lane predicate.