fix: make Prettier checks work on Windows

[dipeshbabu]

Summary

• allow Prettier to accept the checkout's existing line-ending style
• keep formatting checks consistent on Windows when Git checks out text files as CRLF

Why

With core.autocrlf=true, a clean Windows checkout uses CRLF line endings. Prettier's default LF setting causes npm run format:check to report nearly every tracked text file even though the Git worktree is clean.

Setting endOfLine to auto keeps the existing formatting rules while making the check platform-independent.

Validation

• npm run format:check
• npm run typecheck
• npm run lint (0 errors; one warning in generated src/colab-config.ts)
• npm run test:unit (1,156 passing)
• CSpell check used by CI (199 files, 0 issues)
• targeted Prettier check under Node 22.17.0 from .nvmrc