fix: accuracy 1000% bug, Spiele nav icon, light mode polish

- Backend: parseInt for leaderboard values from PostgreSQL
  (string concatenation "1"+"0"="10" caused 1000% accuracy)
- BottomNav: Swords icon instead of emoji for Spiele tab
- Light mode: stronger card shadows and shine gradient

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/src/routes/leaderboard.ts

@@ -101,24 +101,22 @@ router.get('/me', async (req: Request, res: Response): Promise<void> => {
 
     const evaluatedCount = parseInt(tipsStats?.count ?? '0');
     const wrongCount = parseInt(tipsStats?.wrong_count ?? '0');
+    const exactCount = parseInt(String(lb?.exact_count ?? '0'));
+    const tendencyCount = parseInt(String(lb?.tendency_count ?? '0'));
     const accuracy =
       evaluatedCount > 0
-        ? Math.round(
-            (((lb?.exact_count ?? 0) + (lb?.tendency_count ?? 0)) /
-              evaluatedCount) *
-              100
-          )
+        ? Math.round(((exactCount + tendencyCount) / evaluatedCount) * 100)
         : 0;
 
     const response: UserStatsResponse = {
       userId,
       fullName: lb?.full_name ?? req.staffbaseUser!.name ?? 'Unbekannt',
       team: lb?.team ?? null,
-      totalPoints: lb?.total_points ?? 0,
-      rank: lb?.rank ?? null,
-      tipsCount: lb?.tips_count ?? 0,
-      exactCount: lb?.exact_count ?? 0,
-      tendencyCount: lb?.tendency_count ?? 0,
+      totalPoints: parseInt(String(lb?.total_points ?? '0')),
+      rank: lb?.rank ? parseInt(String(lb.rank)) : null,
+      tipsCount: parseInt(String(lb?.tips_count ?? '0')),
+      exactCount,
+      tendencyCount,
       wrongCount,
       accuracy,
     };