[codex] Keep Windows app checkouts on LF

[tianmind-studio]

Summary

• Add a scoped .gitattributes file under desktop/windows.
• Force text files in the Windows app subtree to check out with LF line endings.
• Keep Git checkout behavior aligned with the existing .editorconfig and Prettier setup.

Why

On this Windows checkout, desktop/windows files were written with CRLF because core.autocrlf=true. The Windows app already declares end_of_line = lf in .editorconfig, so ESLint/Prettier reported almost every line as Delete ␍, hiding the real lint findings.

This keeps the policy local to desktop/windows instead of changing the whole repository or weakening Prettier with endOfLine: auto.

Validation

• Before this change on the Windows checkout: ESLint JSON contained 30,011 messages, including 29,948 prettier/prettier messages; sampled messages were Delete ␍.
• git check-attr -a -- desktop/windows/electron.vite.config.ts desktop/windows/eslint.config.mjs desktop/windows/.prettierrc.yaml -> text: auto, eol: lf for all three files.
• Fresh detached worktree from this branch with core.autocrlf=true:
  • desktop/windows/electron.vite.config.ts -> LF 26, CRLF 0
  • desktop/windows/eslint.config.mjs -> LF 32, CRLF 0
  • desktop/windows/src/renderer/src/lib/goals.test.ts -> LF 43, CRLF 0
  • desktop/windows/.prettierrc.yaml -> LF 4, CRLF 0
  • root README.md remained CRLF 174, showing the rule is scoped.
• prettier --check electron.vite.config.ts eslint.config.mjs .prettierrc.yaml src/renderer/src/lib/goals.test.ts in the fresh worktree -> passed.
• Fresh worktree ESLint JSON dropped to 432 total messages, with Delete ␍ count 0; remaining messages are existing real lint/format findings.
• git diff --cached --check -> passed.
• C:\Program Files\Git\bin\bash.exe scripts/pre-commit -> passed.