- Change add_rule parameter from Option<&String> to Option<&str> for better ergonomics
- Use iterator methods (flat_map, any) instead of manual loops and collections
- Collapse nested if conditions using let-else patterns
- Use format string interpolation instead of separate arguments
- Avoid unnecessary String allocations in label comparisons
- Update CLI code to use as_deref() for Option<String> to Option<&str> conversion
- Update all documentation examples and tests to match new API
- All functionality preserved; API is more idiomatic and efficient
