nx_no_cookie_session_test.nx

nx_no_cookie_session_test.nx -- 1:1 runtime proof of the no-cookie session auth (mint -> validate -> realm + negative cases). This is the MONITOR-pillar regression for T#ncs-verify-convention: the verify-success check in nx_ncs_validate_token was `!= 0` (wrong: ed25519_verify_full returns 1 on valid), which rejected every valid token AND would accept invalid ones. main() returns 0 on all-pass, else the failing assertion number.