Add an optional Stage 0 calibration dashboard so CMYK / RIP workflows can
linearize and set ink limits before a full profile. CAL_ artefacts keep
the 5-stage wizard unchanged when calibration is skipped.
printtarg receives -K only for profiling layouts; colprof embeds curves
with applycal. Existing .cal files require Overwrite / Rename / Cancel.
Bump version to v0.8.5.