fix: registry, responsive layout, and strict TypeScript

[DavidHDev]

Combines the approved changes from #1046, #1048, and #1050.

• fixes strict TypeScript errors in SpecularButton and SplitText
• makes the Scroll Stack demo responsive to its container
• ships registry stylesheets as registry:file and regenerates the registry

Validation:

• npm exec tsc -- --noEmit --pretty false
• npm run build
• real shadcn@4.18.0 add smoke test against Aurora-JS-CSS
• visual responsive checks at 1024, 1200, and 1280 widths
• registry validation across all stylesheet entries
• gitleaks scan over the replay commits

Contributor authorship is preserved on each commit.