glmmTMB via RTMB

This project's goal is to improve the accessibility and sustainability of the glmmTMB R package by replacing its C++-based TMB backend with a more user-friendly, R-like RTMB framework. While TMB provides high performance, its reliance on C++ limits contributions from the broader R community. Transitioning to RTMB will lower this barrier and allow more developers to extend the package. I will convert the core computational parts of glmmTMB into RTMB, validate correctness using existing unit tests, and benchmark performance on large datasets. The project will include updating the build infrastructure and improving documentation to support future contributions. The final deliverable will be a fully functional RTMB-based backend with strong performance and increased usability.