compute_fft_copy

Copies a vec2<f32> (re, im) buffer element-wise. Used by nx.gpu.fft* to seed the ping-pong scratch buffer from the caller's input on stage 0 without an extra ping-pong dispatch.

Bindings (see bindings.yaml): src (read), dst (read_write) — both array<vec2<f32>>.

Usage: dispatch by identity with compute.dispatch("@builtin::shaders.compute_fft_copy", ...) — it resolves to the shader's stable guid and auto-compiles on first use (no setup).