nx_smoke_sim.nx

nx_smoke_sim.nx -- end-to-end smoke test of the off-C run-loop. Hand-builds a minimal RV64 Linux ELF that exits with code 42, loads it via nx_loader, runs it via nx_rv64_sim, asserts the exit code matches. Proves the OFF-C verification path works without docker / qemu. This is the smallest possible end-to-end demonstration of the sovereign run-loop: 1. Bytes shaped like an ELF -> nx_loader places PT_LOAD segment at vaddr 0x10000. 2. Entry pc = 0x10000 + 120; PC walks 3 instructions: addi a0, zero, 42 -- a0 = 42 addi a7, zero, 93 -- a7 = sys_exit ecall -- syscall(93, 42, ...) 3. nx_rv64_sim's syscall handler sees nr=93, halts cpu, records exit_code = 42. 4. We assert cpu.halted=1 + cpu.exit_code=42. Run: produces a 0 exit code on success, non-zero on any failure. Pairs with bootstrap_native.sh as the proof-of-concept that the in-NishiLang sim is a viable qemu replacement.