Enhance validation script and CI workflow for code quality checks
- Added support for a --fix option in validate.sh to apply Ruff auto-fixes for code formatting and linting.
- Updated quality-gate.yml to include separate steps for installing development and runtime dependencies.
- Introduced dedicated steps for code formatting checks, linting, type checking, and security analysis in the CI workflow.
Update .gitignore and refactor metrics.py, activities.py, and gates.py for improved clarity and consistency. Added coverage.xml and cache directories to .gitignore. Standardized string formatting and parameter handling in metrics and activities classes, enhancing code readability. Removed the deprecated faker.py file and adjusted related tests accordingly.
