chore: update dependency typescript to v6 (#4697)

* chore: update dependency typescript to v6

* fix: remove deprecated downlevelIteration option for TypeScript 6

downlevelIteration is unnecessary with target ES2022 and now causes
a build error (TS5101) in TypeScript 6.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: explicitly include @types/node for TypeScript 6 compatibility

TypeScript 6 no longer auto-includes @types/* packages from
node_modules. Add explicit "types": ["node"] to ensure Node.js
globals (process, console) and node: imports are resolved.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: escapedcat <github@htmlcss.de>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>