This commit implements several significant improvements to the genSurvPy package:

1. Add competing risks models with both exponential and Weibull hazards

   • Implement flexible covariate generation with different distributions
   • Support for multiple competing risks with cause-specific hazards
   • Add cumulative incidence function calculation utilities

2. Enhance AFT models with log-logistic distribution support

   • Complete implementation of log-normal, Weibull, and log-logistic AFT models
   • Add comprehensive parameter validation

3. Add visualization utilities for survival analysis

   • Create functions for plotting survival curves and hazard functions
   • Implement cause-specific visualization for competing risks

4. Add data quality and summary tools

   • Implement data validation and quality checking tools
   • Add comprehensive dataset summary utilities

5. Improve developer experience

   • Enhance CI/CD workflows with code quality checks
   • Add type annotations throughout the codebase
   • Standardize docstrings with NumPy-style format

This commit addresses multiple items from the project roadmap including
the implementation of new survival models and visualization utilities.