Manifests and receipts unchanged. Each of the 8 group-A identity tests now
extracts its manifest's recorded commit and verifies hashes there instead of
against the current checkout. Tamper assertions and runner source refusals are
kept; missing recorded history is an explicit failure, not a skip or repin.
Drop legacy constructor prose (child=/mutual exclusion), retarget
README and fixed_three_level_multipatch examples to refinements /
level_blocks, and fix stepper error/doc strings that still named
fine_block/base_block or a fixed gap >= 4 (unions use dependency
closure). Wording only; no behavior change.
Rows 2 and ny-3 are ordinary bulk cells that explosion only reads as
donors; only rows 0/1 and ny-2/ny-1 are dropped or reconstructed after
coalescence. Matches the existing y0>=4, y1<=ny-4 slot_reservoir contract.
Adds margin-4 acceptance and margin-3 rejection for a central circle.
Grok