Add .gitattributes file to enforce line endings

[jeremyeder]

Add a file to ensure consistent line endings across different operating systems.

This will help prevent line ending issues (CRLF vs LF) that can cause unnecessary diffs and merge conflicts.

The file should include:

• • Let Git handle line endings automatically
• • Shell scripts should use LF
• • Python files should use LF
• • Markdown files should use LF

This is a simple, low-risk change that improves cross-platform compatibility.