nx_dual_real_llm_emit_test.nx

nx_dual_real_llm_emit_test.nx -- two concurrent v2 LLM actors driving REAL transformer forward, with wall-clock measurement AND stdout TSV emission so operators see the actual numbers the substrate produces. Same workload as nx_dual_real_llm_compose_test (5 iterations per actor, 2 actors interleaved cooperatively). Adds: * Wall-clock measurement around the workload * stdout TSV header + data row labeled "dual_real_v2_5iter" * stdout wallclock_elapsed_us line Substrate ships numbers; smoke driver shows PASS; operator reads the stdout to see real measurement.