Modernize: TypeScript, hooks, rAF springs, tests, fixes for all open issues

[adamcwade]

What this does

Full modernization of the library, closing every open issue.

Library rewrite

• Function components with hooks in strict TypeScript, same public API as v1 (container + ParallaxMousemove.Layer, same props, same springSettings numbers)
• react-motion removed: a small self-contained damped spring integrator (semi-implicit Euler, fixed 60Hz timestep) drives the motion, so the package has zero runtime dependencies
• Animation runs on requestAnimationFrame and writes transforms directly to the DOM node, so mousemove never re-renders React
• prefers-reduced-motion respected automatically, plus an explicit disabled prop
• SSR safe: all window access lives in effects

Issues fixed

• Fixes strange error #1: the prop-type warning came from react-motion, which is gone
• Fixes Use requestAnimationFrame instead of setTimeout #4: requestAnimationFrame replaces the 75ms setTimeout throttle
• Fixes Setting fullHeight prop to true throws error on resize #5: fullHeight keeps height in state instead of mutating the containerStyle prop; a regression test renders with a frozen style object and resizes
• Fixes Declaration file for module not found #8: TypeScript declarations are bundled (dist/index.d.ts, exported prop types)
• Fixes The @babel/plugin-proposal-* packages are deprecated and throw warnings in console while npm install #9: the deprecated babel-preset-stage-0 era toolchain is fully removed

Toolchain

• tsup build: ESM + CJS + .d.ts, proper exports map, sideEffects: false
• vitest 4 + Testing Library: 21 tests covering spring convergence, factor math, retargeting mid-flight, settle-and-stop frame scheduling, unmount cleanup, the frozen-containerStyle regression, reduced motion, and disabled mode
• GitHub Actions CI on Node 20/22/24 (typecheck, test, build)
• npm audit: 0 vulnerabilities
• Version bumped to 2.0.0; README rewritten with full API docs and a v1 migration section

Verified

• 21/21 tests pass, tsc --noEmit clean, build emits ESM/CJS/DTS
• Repo URLs updated to adamcwade

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