nx_quality_driver.nx

nx_quality_driver.nx -- MINIMAL substrate driver: real image -> verdict JSON. Reads /tmp/nx_img.raw (24-byte LE header + raw RGB bytes), runs the safest detectors that don't trip the codegen bug (single function call, no struct returns mid-chain), emits JSON to stdout. svc-quality invokes this as a subprocess per render. Inline-in-main pattern because nxc2 codegen bug forbids the wrapper pattern for some detector compositions. The driver does each detector inline; result fields packed into one flat-array and printed as JSON. Output: {"palette_kind":N,"warm_q10":N,"saturation_q10":N,"mean_r":N,"mean_g":N,"mean_b":N,"image_w":N,"image_h":N}