pub const MATRIX_TO_LED: [[Option<u8>; 21]; 6];Expand description
Maps matrix position [row][col] to a LED index into LED_LAYOUT.
Derived directly from vial.json layout and the sequential LED indices
assigned in LED_LAYOUT. None for dead matrix cells (a!(No) in the
keymap), the layer-toggle columns (5,7 and 5,8), and physical gaps where
no key or LED exists.
To re-verify: for each "row,col" entry in vial.jsons keymap array,
assign the next sequential LED index in reading order (left-to-right,
top-to-bottom), skipping entries that have only position modifiers
(x, y, w, h) and no matrix coordinate.