Lower held card position and add opponent row padding on mobile

Reduce held card overlap offset from 0.35 to 0.15 on mobile portrait
so it doesn't cover the second row of opponents. Increase bottom
padding on opponents row from 6px to 12px for more breathing room.

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

client/app.js

@@ -3544,7 +3544,9 @@ class GolfGame {
         const cardHeight = deckRect.height;
 
         // Position card centered, overlapping both piles (lower than before)
-        const overlapOffset = cardHeight * 0.35; // More overlap = lower position
+        // On mobile portrait, reduce overlap so held card doesn't cover 2-row opponents
+        const isMobilePortrait = document.body.classList.contains('mobile-portrait');
+        const overlapOffset = cardHeight * (isMobilePortrait ? 0.15 : 0.35);
         const cardLeft = centerX - cardWidth / 2;
         const cardTop = deckRect.top - overlapOffset;
         this.heldCardFloating.style.left = `${cardLeft}px`;