WebGPU Water

WebGPU Water, ported as a multi-file TinyFX example from the local WebGPU reference in references/other/webgpu-water, itself based on Evan Wallace's WebGL Water demo.

The port keeps the core pipeline: double-buffered water heightfield feedback passes, sphere displacement, finite-difference normals, refractive/reflective water, caustics, tiled pool walls, and buoyant sphere physics. TinyFX supplies the orbit camera and immediate UI.