Function upload_words 

pub fn upload_words(rect: VramRect, words: &[u32])

Upload an already packed little-endian stream of two 16-bit VRAM pixels per word.

This is the aligned counterpart to upload_bytes. Runtime-generated textures commonly live in a u32 staging arena already, so accepting the packed words directly avoids reconstructing every word from four byte loads while retaining the silicon-safe FIFO transfer path.