Document the producer-private adaptive path, the dummy support workload
diagnostics, the negative result of the old serial binning and the
2026-09-13 full-day comparison (splat 282.944 s vs atomic 481.417 s).
Add the corresponding raw logs, hotspot fixtures and runner evidence,
and lay out the staged plan toward a sub-240 s full-day render without
changing the default atomic path.
wyj
7ddc58515a