nx_probe_caplim_fassign.nx

nx_probe_caplim_fassign.nx -- MUST-REFUSE WITNESS (float-boundary completion, 2026-08-13): the VAR-INIT and plain-ASSIGNMENT sites used to store raw IEEE bits silently even after the let site refused (the 30c re-typed-fix divergence, caught by re-checking the claim). Both shapes below must refuse via the SHARED guard nx_float_bind_guard with the same capability voice + slug capability=float-int-boundary. EXPECT: COMPILE-FAIL, 2 error(s).