Update requirements-dev.txt to add E2E testing dependencies: fakeredis and mongomock for in-memory testing, and include testcontainers for PostgreSQL support.
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.