Avoid repeating the exponential search for odd orders at least nine. Search the even predecessor, translate its row-major placements to the enlarged board, and tile the new border.
Keep direct search and construction explicit so benchmarks can report their costs separately. Verify the routed order-9 result independently and require its search counters to match order 8.
Tests: Release, Debug, ASan and UBSan CTest (8 passed each)
Refs: #6
Codex instance
3e667d6de0