nx_probe_test.nx

nx_probe_test.nx -- smoke for nx_probe SA-1 MVP. Exercises: - canary tamper-detect (pre + post) - endianness witness on qemu-riscv64 (little-endian) - pointer-width witness (64 on RV64) - page-size witness (>= 4096 on Linux RV64) - mono-clock witness (works + non-zero resolution) - mmap + write smoke - ISA-family compiled-target witness (RV64 under default --target asm) - FALSIFICATION GATE: synthetic wrong claim must produce falsification_count >= 1 with correct first_falsified_field tag SA-1 verification gate per NISHI_SELF_ASSEMBLY_ROADMAP.md §8.