nx_esign_pure_gate.nx

nx_esign_pure_gate.nx -- INDEPENDENT GATE over the PURE DECISION CORE of nx_esign_lib. ZERO registry writes, zero I/O: this gate proves the STATUTORY RULES, not the storage. That split is deliberate -- when the seg_store write path stalled ecosystem-wide (debt 1785519597) the rules became unverifiable purely because they sat behind a write. A correctness gate must not be hostage to a storage outage, so the rules now gate independently and in microseconds. Because pure evaluation is free, the four-element test is proven EXHAUSTIVELY over all 16 combinations rather than on hand-picked cases: exactly one of the sixteen may be valid. An exhaustive sweep cannot miss the case a hand-written list forgets. license_tier: ORIGINAL No hw writes (Rule 26). expect_exit: 0