nx_sha256_wasm_vm_gate.nx

nx_sha256_wasm_vm_gate.nx -- proves the byte-width backend fix GENERALIZES beyond the codec, on security-critical crypto, and demonstrates the sovereign WASM VM as a general verifier. nx_sha256_wasm was BLOCKED since 2026-05-16 on the WAT backend memory codegen (its header documents the fallback to browser crypto = sovereignty debt). We compile it with the fixed backend, EXECUTE the shipped wasm in nx_wasm_vm, and check SHA-256 of abc against the FIPS KAT.