a11y: lift the shared Coach icon and info-hint to the 44px touch floor

The top-right Coach hand-off icon button and the info-hint trigger sat
below the WCAG 2.5.5 44px minimum on touch. Grow both hit boxes to 44px
on touch while keeping the visible footprint unchanged — the Coach button
is a fill-less ghost, and the info-hint offsets its padding with an equal
negative margin so inline layout is untouched.

src/components/insights/ask-coach-action.tsx

@@ -146,7 +146,11 @@ export function AskCoachIconButton({
             aria-label={accessibleLabel}
             onClick={() => launch.askCoach(question, scope, autoSend)}
             className={cn(
-              "text-muted-foreground hover:text-foreground size-8",
+              // Keep the quiet 32px visual on pointer surfaces, but grow the
+              // tap target to the WCAG 2.5.5 44px floor on touch (the ghost has
+              // no fill, so the larger hit box is invisible). Matches the
+              // header-action convention on the biomarker detail page.
+              "text-muted-foreground hover:text-foreground min-h-11 min-w-11 sm:size-8",
               className,
             )}
           >

src/components/ui/info-hint.tsx

@@ -36,7 +36,11 @@ export function InfoHint({
             data-slot="info-hint"
             aria-label={t("common.moreInfo")}
             className={cn(
-              "text-muted-foreground hover:text-foreground focus-visible:ring-ring/50 -m-1 inline-flex min-h-6 min-w-6 shrink-0 items-center justify-center rounded-full p-1 transition-colors focus-visible:ring-2 focus-visible:outline-none",
+              // A 44px (WCAG 2.5.5) tap target whose visible footprint stays at
+              // the 24px the icon needs: the 44px box is offset by an equal
+              // negative margin (`p-2.5` + `-m-2.5`), so surrounding inline
+              // layout is unchanged while the touchable area meets the floor.
+              "text-muted-foreground hover:text-foreground focus-visible:ring-ring/50 -m-2.5 inline-flex min-h-11 min-w-11 shrink-0 items-center justify-center rounded-full p-2.5 transition-colors focus-visible:ring-2 focus-visible:outline-none",
               className,
             )}
           >