fix: restore glassmorphism card effects on new components

Apply global .card class to Dashboard, Profile, ConfettiReveal, and
Toast components for consistent glossy card appearance.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/DashboardPage.tsx

@@ -43,7 +43,7 @@ export default function DashboardPage(_props: Props) {
   return (
     <div className={styles.dashboard}>
       {/* Hero Card */}
-      <div className={styles.hero} onClick={() => navigate('/spiele')}>
+      <div className={`card ${styles.hero}`} onClick={() => navigate('/spiele')}>
         <div className={styles.heroLabel}>
           <span>Nächstes Spiel</span>
           {hero && (
@@ -105,17 +105,17 @@ export default function DashboardPage(_props: Props) {
 
       {/* Stats Row */}
       <div className={styles.statsRow}>
-        <div className={styles.statTile}>
+        <div className={`card ${styles.statTile}`}>
           <span className={styles.statValue}>
             {stats.rank !== null ? stats.rank : '—'}
           </span>
           <span className={styles.statLabel}>Dein Rang</span>
         </div>
-        <div className={styles.statTile}>
+        <div className={`card ${styles.statTile}`}>
           <span className={styles.statValue}>{stats.totalPoints}</span>
           <span className={styles.statLabel}>Punkte</span>
         </div>
-        <div className={styles.statTile}>
+        <div className={`card ${styles.statTile}`}>
           <span className={styles.statValue}>{formatStreak(stats.streak)}</span>
           <span className={styles.statLabel}>Streak</span>
         </div>
@@ -127,7 +127,7 @@ export default function DashboardPage(_props: Props) {
           {nudges.map((nudge, i) => (
             <div
               key={i}
-              className={styles.nudge}
+              className={`card ${styles.nudge}`}
               onClick={() => {
                 if (nudge.type === 'untipped') navigate('/spiele');
                 else if (nudge.type === 'leader') navigate('/rangliste');