fix(core): preserve settings from adopted lint configs

[skoshx]

Summary

• preserve third-party plugin settings when React Doctor adopts .oxlintrc.json or .eslintrc.json
• read settings even when Oxlint cannot use an ESLint config through extends
• use the existing JSONC parser and protect generated settings from prototype keys
• add focused unit and end-to-end Tailwind regressions

Product check

• User job: keep existing lint plugin configuration active during a React Doctor scan.
• Reuse: extend the existing lint-config detection and generated Oxlint config.
• Telemetry: existing rule.fired and lint.failed signals cover adopted plugin behavior. No new metric is needed.
• Kill metric: revert settings adoption if adopted-config scans increase lint.failed by more than 1% across two releases.

Validation

• nr test
• nr lint
• nr typecheck
• nr format:check
• nr build
• nr smoke:json-report
• focused core and CLI regressions
• one separate performance threshold failed once during the concurrent suite, then passed three direct reruns and the full-suite rerun

Closes #1694

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/eslint-plugin-react-doctor@1695

npm i https://pkg.pr.new/oxlint-plugin-react-doctor@1695

npm i https://pkg.pr.new/react-doctor@1695

commit: 6a3235e

[github-actions]

React Doctor found no new issues. 🎉

_{Reviewed by React Doctor for commit 6a3235e.}

[github-actions]

Interactive terminal E2E

Terminal Control verified the built CLI at 6a3235e in a real PTY:

• selected a project interactively and observed Scanning... before the three-second Git delay completed
• waited for the clean result and exercised the compact report
• opened copy context and the GitHub Actions confirmation, then cancelled safely

Download the edited MP4 and PNG evidence