Add .gitattributes to enforce LF line endings for shell scripts

- Ensure all .sh files use LF (not CRLF) for Linux compatibility
- Fix CRLF line ending issues causing script failures in CI
- Configure eol=lf for .sh, .py, .yaml, .md files

Author: thc1006

.gitattributes

@@ -0,0 +1,16 @@
+# Ensure shell scripts always use LF line endings
+*.sh text eol=lf
+
+# Python files
+*.py text eol=lf
+
+# YAML files
+*.yaml text eol=lf
+*.yml text eol=lf
+
+# Markdown and documentation
+*.md text eol=lf
+
+# Windows-specific files can use CRLF
+*.bat text eol=crlf
+*.ps1 text eol=crlf