fix(cabinet): equal-height StatCards so dashboard balance/referral align

In a grid, the wrapping <Link> stretched to the row height but the
StatCard inside only took content height, so the referral card (which has
a subValue line) rendered taller than the balance card ('один толще
другого'). Make StatCard fill its cell with h-full and stretch the
StatsGrid links. Verified by rendering both cards against the built CSS:
balance 86px->94px, now equal to referral's 94px.

src/components/dashboard/StatsGrid.tsx

@@ -24,7 +24,7 @@ export default function StatsGrid({
 
   return (
     <div className="grid grid-cols-2 gap-2.5">
-      <Link to="/balance" className="block" data-onboarding="balance">
+      <Link to="/balance" className="block h-full" data-onboarding="balance">
         <StatCard
           label={t('dashboard.stats.balance')}
           value={`${formatAmount(balanceRubles)} ${currencySymbol}`}
@@ -33,7 +33,7 @@ export default function StatsGrid({
           trailing={chevron}
         />
       </Link>
-      <Link to="/referral" className="block">
+      <Link to="/referral" className="block h-full">
         <StatCard
           label={t('dashboard.stats.referrals')}
           value={`${referralCount}`}

src/components/stats/StatCard.tsx

@@ -50,7 +50,7 @@ export function StatCard({
   const trendStyle = delta ? (TREND_STYLES[delta.trend] ?? TREND_STYLES.stable) : null;
 
   return (
-    <div className="rounded-xl bg-dark-800/30 p-3 transition-colors hover:bg-dark-800/50">
+    <div className="h-full rounded-xl bg-dark-800/30 p-3 transition-colors hover:bg-dark-800/50">
       <div className="flex items-center justify-between gap-2">
         <span className="truncate text-xs text-dark-500 sm:text-sm">{label}</span>
         {trailing}