Origami Crane Flock: V-Formation Flight (2D)

This 2D companion drives the same V-formation logic as the 3D Origami Crane Flock, viewed from above: a leader crane follows a closed flight loop, the rest of the flock computes a lateral/forward offset from that leader's heading exactly as the 3D version does with its right/up/forward basis, and each bird's wings flap on a per-bird phase-offset sine wave so the flock reads as a living formation rather than a synchronized animation. The Reform button snaps every crane straight onto its formation slot, useful for seeing the V-shape clearly before it eases back into a smooth follow.