Complete leaf to deltaspace terminology migration

- Update all function parameters, variable names, and comments
- Replace 'leaf' with 'deltaspace' in logging and documentation
- Update test files and method names for consistency
- Maintain 100% test coverage and functionality
- Add temp_downloads/ to .gitignore

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -81,4 +81,7 @@ docs/_static/
 docs/_templates/
 
 # Logs
-*.logsrc/deltaglider/_version.py
+*.log
+
+# Temporary downloads
+temp_downloads/