Petween Physics: A Throwing Physics Plugin for Petween

`petween-physics` is a physics-engine add-on plugin for `petween` within the DSH ecosystem, adding interactive behaviors such as gravity, bouncing, drag-and-throw, and ground sliding. It supports semi-implicit Euler integration and includes collision deformation, sprite-frame feedback, and persistent settling logic. Installation requires Node.js ≥ 22.18 and the `petween` plugin, and can be completed by registering it with DSH. Configuration files are stored in `~/.dsh/petween-physics/`, with tunable parameters such as gravity, elasticity, friction, and collision boxes. It uses a dual-host architecture, supporting both Web and the `Petween Desktop` application, and has a clear source structure that is easy to extend.