Add .gitattributes to fix line endings for Windows devcontainer users

[madebygps]

I was testing out our repo on Windows in a devcontainer and azd up failed with /bin/sh: 1: ./infra/auth_init.sh: not found, even though the file existed.

Windows Git defaults to converting line endings to CRLF (users can disable this, some don't, like me), which breaks shell scripts in the devcontainer.

Added a .gitattributes file to enforce correct line endings per-repo, so it works for everyone automatically.

[Copilot]

Pull request overview

This PR adds a .gitattributes file to enforce consistent line endings across platforms, specifically to prevent Windows Git's default CRLF conversion from breaking shell scripts that run in Linux devcontainers. The fix addresses the immediate issue where auth_init.sh failed to execute in a Windows devcontainer due to incorrect line endings.

Key Changes:

• Added .gitattributes with text=auto for automatic text file detection and LF normalization
• Configured LF line endings for shell scripts, Python files, Dockerfiles, and configuration files used in Linux containers
• Configured CRLF line endings for Windows-specific scripts (.bat, .cmd, .ps1)
• Marked binary file types appropriately

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[Copilot]

The pattern 'entrypoint.sh' is redundant since line 5 already covers all '*.sh' files, which includes 'entrypoint.sh'. This redundant rule should be removed to keep the configuration cleaner and avoid confusion.

[pamelafox]

LGTM, I've had to do similar before:
https://github.com/Azure-Samples/azure-search-openai-demo/blob/main/.gitattributes