box3d: recording op stream (capture side)

All ~140 opcodes from recording_ops.inl with exact C values, capture hooks
in every mutator and query (~137 sites across body/shape/joint/world),
48-byte header with registry locator backpatch, snapshot seed, query tag
interning, state-hash anchors per step. Recording is observer-only
(bit-identical world state with and without a recording attached).
Replay/player side lands separately.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>