[nicolas-godefroy-dev]

Summary

Moves the repo to a new toolchain. The library's runtime code (src/, ios/, android/, plugin/) is unchanged.

• Package manager: yarn → pnpm workspace (example/ is a workspace package). Node is pinned with mise via .tool-versions, and pnpm through packageManager + corepack. The xcode>uuid resolution is now a pnpm override.
• Lint/format: ESLint + Prettier → oxlint (type-aware) + oxfmt.
• Git hooks: husky + lint-staged → lefthook. Pre-commit runs oxlint and oxfmt on staged files, then tsc and Jest. Commit-msg runs commitlint (bumped to v21).
• Deps: Expo SDK 58 / React Native 0.88 / React 19.3 / TypeScript 6 in dev dependencies and the example app. Peer ranges are unchanged.
• Config: commitlint.config and the example's metro.config are now TypeScript. .npmignore is removed; files in package.json already controls what gets published.
• CI: actions pinned to commit SHAs (Renovate keeps the digests updated), and workflows use mise + pnpm. Renovate dedupes with pnpm.
• Example app: marked private, uses the Metro web bundler, and logs every billing agreement option.
• Docs: CONTRIBUTING rewritten for the new toolchain. Added CLAUDE.md.

Motivation

The old setup had yarn v1, ESLint 8, husky 8 and commitlint 17, all outdated. This replaces them with faster, maintained tools and gets the dev setup down to mise install && corepack enable && pnpm install.

Testing

• pnpm typecheck, pnpm lint and pnpm test pass locally.
• I tested this manually (example app on iOS/Android)
• I added automated tests

Documentation

• I have added relevant documentation for my changes.
• This PR does not result in any developer-facing changes.

[linear-code]

ENG-3276