--draw-mesh no longer modifies the primary render. The clean HDR FITS and
tone-mapped image are written first, then the final image-plane mesh is
overlaid in place on the already-consumed HDR buffer and saved as a
<stem>_mesh sibling. This applies uniformly to single-frame, movie-frame,
and imported lens-map renders, with derived paths validated before catalog,
spacetime, and render initialization.
Dummy PSF backends still write nothing and report ignoring --draw-mesh. The
reference-image target now uses the configured image extension so the
ENABLE_PNG=0 test path passes, and the CLI tests cover clean-main identity,
sibling naming, PATH_MAX overflow, and zero-tolerance HDR comparison.
README, README.zh-CN, and usage.md describe the new naming; the mesh reference
asset is renamed to match.
Replace the artifact-affected Schwarzschild image with the corrected 4K render. Link both READMEs to the paired CPU/HIP benchmark and clarify that this run had no PSF wing clipping or direct fallbacks.
wyj