tourr: new PP indices based on scagnostics

This project will extend the tourr R package by adding new projection pursuit indices (PPIs) based on scagnostics, so users can search for a wider range of visually meaningful structures in high-dimensional data. I plan to identify which scagnostic measures are suitable for use as PPIs, implement them in tourr, and test them carefully on simulated datasets where known patterns are hidden among noise variables. I will also compare optimiser strategies, including the jellyfish optimiser, to evaluate which methods recover these structures most effectively and efficiently. The main deliverables will be new scagnostics-based PPIs in tourr, tests written with testthat, examples and vignettes explaining how to use the new functionality, and package-quality documentation and checks to prepare the contribution for practical use and future CRAN submission.