feat(a11y): add aria-label to clickable media cards

The hero carousel video card and use-cases grid image card already had
role="button", tabIndex={0}, and onKeyDown handlers. Adds the missing
aria-label so screen readers announce what each clickable card does.

Both cards now use aria-label={`Expand ${title}`}, matching the example
in the issue.

Fixes #913

surfsense_web/components/homepage/use-cases-grid.tsx

@@ -68,6 +68,7 @@ function UseCaseCard({
 				<div
 					role="button"
 					tabIndex={0}
+					aria-label={`Expand ${title}`}
 					className="cursor-pointer overflow-hidden bg-neutral-50 p-2 dark:bg-neutral-950"
 					onClick={open}
 					onKeyDown={(e) => {

surfsense_web/components/ui/hero-carousel.tsx

@@ -118,6 +118,7 @@ function HeroCarouselCard({
 				<div
 					role="button"
 					tabIndex={0}
+					aria-label={`Expand ${title}`}
 					className="cursor-pointer bg-neutral-50 p-2 sm:p-3 dark:bg-neutral-950"
 					onClick={open}
 					onKeyDown={(e) => {