🦔 Porcupine Sentinel Warning System (2D)

This 2D companion drives the same sentinel-scan mechanic as the 3D scene through a plain top-down canvas: a fraction of the group takes a sentinel role, each on its own phase clock, and raises a quill-flare alert once predator risk pushes its scan threshold. Every alert emits a ripple that pulls the rest of the group toward the den, with the pull strength set by the signal-transmission slider.