proc_field_noise (compute shader)

2D value-noise field: dst[i] = value2(seed, coords[i] * freq). One GPU thread per element. Re-implements proc.noise.value2 — the integer FNV-1a lattice hash (proc.hash.hashInts) is bit-exact-portable, so the u32 hash here matches the Luau bit32 hash exactly; the quintic-faded bilinear interpolation runs in f32 (vs the CPU's f64), bounded to f32 rounding.

It reads coords (one vec2<f32> per element) and writes dst (one f32 per element); seed (int, default 0) and freq (float, default 1.0) are its params. The gpu.noise op (proc.gpu.eval("noise", { input = coords, count = n, seed = 7, freq = 0.1 })) dispatches it and returns dst as a GPU-backed Field.