feat: add rainbow cursor component

[Kshitijasharma]

Description

Adds Rainbow Cursor, a cursor ribbon with a yellow-to-blue-to-purple gradient, smooth tracking, a tapered tail, and subtle glow.

Changes

• Add the RainbowCursor component using OGL.
• Add configurable colors, ribbon width, tracking speed, glow, opacity, and idle fading.
• Add a demo, documentation, and sidebar navigation.
• Register the component and demo, including generated registry artifacts.

Motivation

Adds a glowing cursor ribbon for interactive sections, with three-color transitions, smooth tracking, and a tapered tail. I have always been fascinated by different cursor styles, as they can make the website experience more engaging!

Breaking Changes

None. This adds a new component.

Screenshots

Port: localhost:3000
Browser: Chrome

rainbow-cursor-demo.mp4

Testing

• pnpm --filter=www check completed successfully.
• pnpm --filter=www build completed successfully.
• pnpm build:registry completed successfully.
• Visually checked the ribbon effect in the local demo.

ESLint reports two existing warnings in dia-text-reveal.tsx, which is unchanged by this contribution.

The root Turbo commands encountered a local cache-writing issue on Windows. The direct package checks and production build completed successfully.

Checklist

• Local checks pass using pnpm --filter=www check.
• Production build passes using pnpm --filter=www build.
• pnpm build:registry was run.
• Confirm generated registry files are committed and the working tree is clean.
• PR title follows Conventional Commits: feat: add rainbow cursor component.

[vercel]

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