fix(grille): use CanvasText directly for row background to fix iOS borders

iOS Safari does not reliably propagate the color property across shadow
DOM boundaries, so background: currentColor on rows resolved to the same
value as Canvas, making grid borders invisible. Using CanvasText directly
matches how bar text and diagonal lines are already coloured, and does not
depend on shadow DOM colour inheritance.

Author: nelstrom

packages/grigson-grille-harmonique-renderer/src/styles.ts

@@ -54,7 +54,7 @@ export function getGrilleStyles(typeface: string = 'sans'): string {
 [part~="row"] {
   display: flex;
   gap: var(--cg-grid-width);
-  background: currentColor;
+  background: CanvasText;
   padding: var(--cg-grid-width);
   width: fit-content;
   margin-bottom: calc(-1 * var(--cg-grid-width));