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>

components/pinball/PinballCanvasImpl.tsx

@@ -68,7 +68,7 @@ export default function PinballCanvasImpl({ tableData, rom, tableInfo }: Pinball
               real coin-op cabinet — pressing 1 alone does nothing until a
               credit is added. Surfaced here since it's the first thing
               anyone hits and easy to mistake for the app not responding. */}
-          <p className="font-mono text-xs text-chrome">
+          <p className="max-w-md px-4 text-center font-mono text-xs text-chrome">
             If Start doesn&apos;t respond: press <span className="text-arc">4</span> to insert a coin, then{" "}
             <span className="text-arc">1</span> to start.
           </p>