Quorum-Sensing Field: Autoinducer Diffusion Wave

This is the spatial counterpart to the 3D squid light-organ simulator. Instead of one shared population number and one shared signal number, the autoinducer that Vibrio fischeri secretes is modeled as a concentration field that must physically diffuse across the crypt before every bacterium can "feel" the same signal — so the quorum switch does not flip everywhere at once, it spreads as a wave from wherever colonization is densest. The bacterial population still grows logistically at each point, but the reaction-diffusion coupling between population and signal is a genuinely 2D-native mechanism, not a flattened view of the 3D scene.