repository: normalize line endings with Git attributes

[rameel]

Summary

• Add * text=auto to .gitattributes so Git normalizes text files and handles checkout line endings according to user configuration.
• Normalize 151 existing tracked files from CRLF to LF in the repository.

Verification

• Verified that all changes to existing files consist only of CRLF-to-LF normalization.
• Verified that all tracked text files are stored with LF in the Git index.
• The Build & Test workflow passed Debug and Release builds and tests on x64 and ARM64, including the SIMD-disabled configurations.

Prepared by GPT-6 Astra.