Polish home CTAs, panel rounding, and 404 label; fix dev-mode SW crash

- Shorten CTA labels to "Play Demo" / "Load Table"
- Fix mismatched corner radii on the hero and table-staging panels
- Add horizontal padding to the in-game "insert coin" hint on mobile
- Match the 404 page's "TILT" eyebrow label size to the rest of the site
- Only register the service worker in production — it precaches
  /404.html, which doesn't exist as a static file under `next dev` and
  was failing cache.addAll() on every load

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/not-found.tsx

@@ -4,7 +4,7 @@ import { buttonClassName } from "@/components/ui/Button";
 export default function NotFound() {
   return (
     <main className="flex flex-1 flex-col items-center justify-center gap-6 px-4 py-24 text-center">
-      <p className="font-mono text-sm tracking-[0.3em] text-arc">TILT</p>
+      <p className="font-mono text-xs tracking-[0.3em] text-arc">TILT</p>
       <h1 className="font-display text-5xl font-black tracking-wide text-marquee sm:text-7xl">
         TABLE NOT FOUND
       </h1>