* config: add .gitattributes for cross-platform line ending consistency
- Add comprehensive .gitattributes to normalize line endings
- Ensure shell scripts always use LF (required for Unix execution)
- Mark binary files explicitly to prevent corruption
- Eliminate CRLF warnings for Windows contributors
- Follow cross-platform best practices
This fixes persistent 'LF will be replaced by CRLF' warnings that
confuse Windows contributors during normal git operations.
Fixes#950
* fix: add trailing newline at end of file
Per review feedback from @Hundao
Richard Tang