Fixes#78445.
- Use piped stdio for the post-core update child on Windows so the child and descendants do not inherit the parent console handles.
- Relay child stdout/stderr back to the parent when piped so update output remains visible.
- Keep non-Windows behavior on inherited stdio.
- Add focused coverage for the stdio resolver.
Verification:
- `pnpm vitest run src/cli/update-cli/update-command.test.ts`
- `pnpm build`
- `pnpm exec oxlint src/cli/update-cli/update-command.ts src/cli/update-cli/update-command.test.ts`
- Full GitHub CI green at `321608e00ba118421ea65124f494458ed229defd`.
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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