Overlap-ring design ratified 07/17: the blocking entry refactored into
pose_scene_dp_submit (through the parent enqueue; fence style + sync/async
launch switchable) + pose_scene_dp_readback (the one-end-of-scene D2H +
status checks) - the blocking entry composes both, byte-identical ABI and
behavior, retained for the D4 oracle + A/B. New exports:
- tp_proc_exec_pose_scene_dp_launch: GPU-side cudaStreamWaitEvent on the
  active ring set's ready event (replaces the host-blocking bayer_fence),
  raw enqueue with NO cuCtxSynchronize, returns immediately; one chain in
  flight, want_trace/want_mstats fixed at launch.
- tp_proc_exec_pose_scene_dp_collect: readback (first D2H = completion wait),
  returns last-cycle npk exactly like the blocking entry.
Case scene_dp_split (test_pose_scene_dp_split_jna, rides captured pose_corr):
4 chains launch/collect bit-identical to the host-driven B3 loop, with
chains 2-4 running CONCURRENT ring-set-1 staged uploads + async conditioning
during the chain (set-1 result bit-exact vs the sync-path reference).
run_cases.sh ALL PASS incl. blocking scene_dp unchanged; sanitizer 0 errors.
Co-authored-by: Claude Opus 4.8 <claude-opus-4-8@anthropic.com>
Co-authored-by: Claude Fable 5 <claude-fable-5@anthropic.com>