Function emit_xpu_soc_verilog 

pub fn emit_xpu_soc_verilog(name: &str, k: usize, n_in: usize) -> String

Emit the XPU SoC: a byte-stream loader (byte_in/byte_valid) filling an on-chip frame buffer, on-chip assembly of the engine’s config + inputs, and the k-cell execute engine — done + result when the whole frame has arrived.