Fix Ballpit background not reacting to parameter change

[DarkFalc0n]

The Ballpit background did not react to parameter changes in Background Studio when props were updated.

Cause

The Ballpit component initialized the createBallpit physics/rendering instance once inside a mount useEffect, but had no mechanism or useEffect to listen to subsequent prop updates and sync them to the running instance, nor an updateConfig handler on the instance.

Changes

• Live configuration updates: Added updateConfig method to createBallpit to handle dynamic prop updates. If count changes, it re-initializes the spheres buffer; for other parameters (e.g. colors, minSize, maxSize, size0), it updates the live config, colors, and physics sizes dynamically.
• Prop sync effect: Added a useEffect hook in Ballpit component to sync updated props and followCursor to spheresInstanceRef (skipping initial render via isFirstRender ref).
• Applied identically across all four variants: content (JS/CSS), tailwind (JS/TW), ts-default, ts-tailwind.
• Synced the embedded source in the generated public/r/Ballpit-{JS,TS}-{CSS,TW}.json registry files.

useEffect(() => {
  if (isFirstRender.current) {
    isFirstRender.current = false;
    return;
  }
  if (spheresInstanceRef.current) {
    spheresInstanceRef.current.updateConfig({ followCursor, ...props });
  }
}, [props, followCursor]);

• Fixes [BUG]: Background Ballpit not reacting in Background Studio to parameter change. #1012