CDN-368: The Two-Body Contrast Field

CDN-368 turns a geometric intuition about two particles moving through textured space into a locked stochastic two-body simulation. The model separates common-mode environmental flow, which cancels from the pair’s relative coordinate, from differential tidal texture, which competes with coherent pair attraction. It defines the contrast parameter C0=a_pair(r0)/σ_delta_env(r0) and shows a capture/coherence threshold near C50=0.657, with low-contrast trials mostly disrupted and high-contrast trials coherently captured. The release includes simulation code, contrast sweeps, sample trajectories, common-mode cancellation tests, figures, prediction hashes, and validation notes.