nx_probe_ptrfield_idx.nx

nx_probe_ptrfield_idx.nx -- MINIMAL REPRO for debt 1786057660. CLAIM UNDER TEST: nx_cc miscompiles `structptr.field[i]` when `field` is a pointer to a NON-BYTE type. Isolated by differential bisect in nx_linemap.nx (three *i64 fields); this probe strips that finding to the smallest shape that can still exhibit it, so the verdict is about the LANGUAGE FEATURE and not about the line map. The estate's existing instance of the pattern is ctx.out[pos] in nx_import.nx, where the field is *u8 -- element size 1, so an element-size scaling error is invisible BY CONSTRUCTION. Every other *i64 indexing site nearby (canonicalise_path) uses a LOCAL handle. So the codebase avoided this shape by accident, not by design, and nothing tests it. Exit codes name the exact failing direction rather than a single boolean: 0 = no defect: field-index and hoisted-local addressing agree, both directions 11 = write-via-field / read-via-local disagreed at index 0 (base or scale wrong) 12 = ... at index 1 (index 0 agreeing but 1 not => SCALE, not base) 13 = ... at index 2 14 = write-via-local / read-via-field disagreed (the reverse direction) 15 = *u8 control FAILED -- if this fires the defect is broader than non-byte pointers and the whole diagnosis in 1786057660 needs rewriting