Introduces a three-layer defence against CRLF/LF drift:
- `.gitattributes` normalizes all text files to LF on commit and checkout;
Windows-native scripts (*.bat, *.cmd, *.ps1) explicitly keep CRLF.
- `.editorconfig` instructs editors (VS Code, JetBrains, vim, etc.) to save
with LF by default so the problem is prevented at the source.
- `mixed-line-ending --fix=lf` hook in pre-commit catches anything that
slips through and auto-fixes it before commit.
No file contents are normalized in this commit — that follows in a
separate `git add --renormalize .` commit for easier review.
