Full-height skyline columns partition the remaining board. Add sound gcd and bounded subset-sum checks for the resulting component areas, with boundary-event and periodic benchmark schedules.
Keep the rules disabled by default because their small tree reductions do not recover their measured cost. Record the rejected default and scheduling evidence so it can be revisited only with new data.
Tests: Debug CTest (14 passed)
Tests: ASan+UBSan CTest (14 passed)
Refs: #13
Codex instance
39ff5cb340