nx_compute_runner_test.nx

nx_compute_runner_test.nx -- end-to-end loop closure. Build a real graph -> run it -> get real tensor output -> verify via numeric oracle vs hand-computed reference. All pure NishiLang. This is the "world class without comfyui annoyance but with the power and more" deliverable: typed DAG + content-addressed nodes + kernel dispatch + numerical verification, in one .nx program.