nx_option_enforce_ok.nx

nx_option_enforce_ok.nx -- LN2 POSITIVE CONTROL: every narrowing idiom the mode recognises, in one program that must compile under `--optenforce` AND run to exit 0 under both modes. A deny mode that refuses everything fails HERE, and a mode that missed one idiom would refuse real code. I1 `if p == 0 { return }` early exit -> p non-null for the rest of the block I2 `if p != 0 { ... }` -> non-null inside the then-block I3 `if (p as i64) == 0 { return }` -> the cast-shaped early exit I4 `while q != (0 as *OkNode) { ... }` -> non-null inside the body I5 `if p == 0 { } else { ... }` -> non-null inside the else-block I6 nx_assert_ptr(p as *u8, "...") -> non-null for the rest of the block I7 `let s = &local` -> bound non-null, no guard needed I8 a `var` pointer re-checked after reassignment I9 the write legs: `p.f = v`, `*p = v` after a guard license_tier: ORIGINAL No hw writes (Rule 26).