Approved design for the cell-relative physics frame port: retire
_liveCenter from physics (render-only), carry Position{ObjCellId,
Frame{local in [0,192), quat}} as the source of truth, port
get_block_offset (verified 0x0043e630 nets to delta-landblock * 192 m),
translate inter-tick collision state per-cell like retail (0x0050a592).
7-slice parallel-frame migration; conformance via transform-on-read (no
fixture re-capture).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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