nx_sext_wasm_kat_gate.nx

nx_sext_wasm_kat_gate.nx -- END-TO-END KAT for the WASM lane's subword sign-extend fix (2026-07-10): forks the sovereign pipeline (nx_compile_wat: .nx -> wat; nx_wat_compiler: wat -> wasm) on nx_sext_wasm_kat.nx, loads the wasm in nx_wasm_vm, and asserts the SEMANTICS in-VM: T1 both tools rc=0 (pre-fix: nx_wat_compiler REFUSED -- i64.store32/load32_* were unknown atoms) T2 exports resolve T3 sext_kat() == 0 (*i32 negative+positive round-trip AND *u8 0xA0->160 witness, all in-VM) T4 sext_load_neg() == -100 (the visible sign-extension number; a zero-extend lane returns 4294967196) This is the WASM twin of nx_i32store_probe_gate (x86) -- one language semantic, every backend. Stage first: nx_sov_build_run nx_compile_wat --build-only + nx_sov_build_run nx_wat_compiler --build-only. expect_exit: 0 license_tier: ORIGINAL