Function emit_state_plane_testbench 

pub fn emit_state_plane_testbench(
    name: &str,
    n_in: usize,
    n: usize,
    max_cycles: usize,
) -> String

A self-checking testbench for a state-plane controller: for each of n input vectors, pulse rst, drive in{k}, run until done (bounded by max_cycles), and compare result against the VM oracle loaded from state_{name}_{in,out}.hex. Mirrors emit_loop_fabric_testbench (the CGRA clocked harness).