nx_triangulation_algebra.nx

nx_triangulation_algebra.nx -- L5 verification of algebraic properties that nx_int satisfies. Each property tested here is shared with MANY mathlib4 / Coq / HOL theorems by name pattern: add_comm, mul_assoc, mul_zero, etc. When the substrate proves the property for nx_int across multiple sample inputs, it gives an L5 verdict that AUTHORIZES the shape- matching theorems in the QED corpus to claim PROVED-on-nx_int. This is not Lean transpilation -- it's an honest substrate-side proof that the SAME ALGEBRAIC IDENTITIES hold in NishiLang.