Replaced class() with inherits() in sign_importance.R.
Increased test coverage (~70%).
Updated R dependency to R (>= 4.6).
Replaced S4 slot access with accessors in code and documentation.
Removed unused helper functions.
Improved namespace imports and reduced use of ::.
Refactored selected loops using vectorized/*apply approaches.
Improved message/stop construction.
Updated documentation and vignette (runnable examples, chunk labels).
Minor update (trigger rebuild)