feat: configure responsive image sizes for optimized loading

- Added custom deviceSizes configuration in next.config.ts to support common mobile and desktop breakpoints
- Added responsive sizes attribute to hall wallet strip background image for proper srcset generation

src/features/hall/hall-wallet-strip.tsx

@@ -91,6 +91,7 @@ export function HallWalletStrip() {
           src="/entry/image5.png"
           alt=""
           fill
+          sizes="(max-width: 768px) 100vw, 768px"
           className="pointer-events-none object-cover object-center"
           aria-hidden
         />