fix(core): preserve settings from adopted lint configs (#1695)

* fix: adopt settings from existing .oxlintrc.json

- Read settings from adopted lint configs via readAdoptedLintConfigSettings
- Merge adopted settings (e.g. tailwindcss.entryPoint) with react-doctor settings
- Exclude react-doctor settings from adoption to avoid circular override
- Add comprehensive tests for settings adoption and merging
- Add user-tailwind-config fixture to verify Tailwind settings adoption

Fixes #1694

Co-authored-by: Skosh <skoshx@users.noreply.github.com>

* chore: add changeset for settings adoption fix

Co-authored-by: Skosh <skoshx@users.noreply.github.com>

* fix(core): preserve adopted lint settings

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Skosh <skoshx@users.noreply.github.com>
Co-authored-by: Aiden Bai <aiden@million.dev>