v5: carrier detection uses a dedicated green model tint and the first-person shader renders the carrier unconditionally.
Night Vision is intentionally NOT detected from Sampler2: in modern Minecraft item/UI lightmaps are not a reliable NV-state signal. The datapack should give the carrier while NV is active and remove it when NV ends. GUI remains a normal cursor icon via display_context.
CMD: 0/default, 1, 2.
Carrier marker tint: RGB [0,1,0].
