chore: upgrade Node.js and npm dependencies

[meixg]

Summary

• Upgrade the project runtime baseline to Node.js 22.13+ and npm 10.9.2+
• Upgrade production and development dependencies with a regenerated npm lockfile
• Adapt the TypeScript compiler integration and custom ESLint rules to the upgraded toolchain
• Migrate the demo from koa-router to @koa/router

Validation

• npm ci
• npm test — 60 passing
• npm run build
• npm run lint
• npm run doc
• CLI smoke test
• npm audit --omit=dev --audit-level=high — 0 vulnerabilities

Note

• PHP runtime regression could not run in this environment because PHP and the repository's test/runtime/phpunit binary are unavailable.