Mobile: make in-game/post-match overlays scroll-safe on short screens

- GameTable Backdrop (Hakem/Trump/Round/Match-over): scroll when taller than the
  viewport via overflow-y-auto + min-h-full centering — no more clipped panels.
- DailyRewardModal: cap height + scroll (was overflow-hidden, clipped the 7-day grid).
- PostMatchRewardsModal: max-h uses dvh (mobile chrome safe).
- ScreenShell: add overflow-x-hidden so a too-wide child can't scroll horizontally.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/GameTable.tsx

@@ -900,9 +900,10 @@ function Backdrop({ children }: { children: React.ReactNode }) {
       initial={{ opacity: 0 }}
       animate={{ opacity: 1 }}
       exit={{ opacity: 0 }}
-      className="absolute inset-0 z-40 flex items-center justify-center bg-navy-950/70 backdrop-blur-sm p-5"
+      className="absolute inset-0 z-40 overflow-y-auto overscroll-contain bg-navy-950/70 backdrop-blur-sm"
     >
-      {children}
+      {/* min-h-full + centering: centers short panels, scrolls tall ones (no clip). */}
+      <div className="flex min-h-full items-center justify-center p-4 py-8">{children}</div>
     </motion.div>
   );
 }