🦫 Beaver Life Colony Simulator: Lodge, Dam, Winter Survival, Energy and Habitat Lab — 2D Pond Cross-Section and Phase Plane

2D companion of the beaver colony lab: a side cross-section of the dammed pond with weir and seepage flows, Stefan ice and the lodge, a pond level versus inflow phase plane, and a winter food-cache energy budget. Uses the same model module as the 3D version.