fix(ScrollVelocity): default parallax/scroller class in tailwind variants

[MauryaQbit]

Fixes #1078.

The Tailwind variants of ScrollVelocity rendered a literal undefined class on every default usage because parallaxClassName / scrollerClassName had no defaults while the render path interpolates them:

<div className={`${parallaxClassName} relative overflow-hidden`}>

Changes

• src/tailwind/TextAnimations/ScrollVelocity/ScrollVelocity.jsx: parallaxClassName = 'parallax', scrollerClassName = 'scroller'
• src/ts-tailwind/TextAnimations/ScrollVelocity/ScrollVelocity.tsx: same
• public/r/ScrollVelocity-JS-TW.json, public/r/ScrollVelocity-TS-TW.json: regenerated content for the two affected variants only (patched without line-ending churn; full registry:build touches 687 files on Windows, so unrelated files left untouched per fix(LetterGlitch): smooth colour transitions freeze after one frame #1070 precedent)

Aligned to the majority + docs (content / ts-default / ScrollVelocityDemo.jsx:82,88 already use 'parallax' / 'scroller'), following the #1060 variant-parity precedent. '' would also remove undefined but would fail check:prop-docs variant agreement.

Testing

• Repro before: `${undefined} relative overflow-hidden` -> "undefined relative overflow-hidden"; after: "parallax relative overflow-hidden", custom values still pass through.
• npm run check:prop-docs PASS (1934 defaults, 171 tables/components).
• npx eslint src/tailwind/TextAnimations/ScrollVelocity/ScrollVelocity.jsx --max-warnings 0 PASS.
• npx tsc --noEmit --skipLibCheck PASS.
• Verified desktop/mobile preview path unchanged (demo uses content variant explicitly; TW change only replaces undefined token with documented default).