Receipt — black & white for thermal (prod)

Gate 2 4/4 passed · 51/51 regression. Narong: gray/colour prints poorly on the thermal printer — just black for everything. The order receipt and the close-shift report now render pure black on white: the muted-gray labels, the green quantity/totals, and the light-gray dividers are all black (dashed/dotted line styles kept for separation, just in black); the shift report's over/short and footer are black too (over/short stays bold). Verified on prod by sampling every text element in the reprint receipt — all compute to rgb(0,0,0). nix-cafe 0946e16, no migration.