Individual TWT wire-codec checkpoint on ns-3.48 Local acceptance: 77 test cases and both physical probes passed; 18 cases cover byte layouts, bounded parsing and explicit timing conversion. Scope: ordinary individual IE and unprotected S1G Setup/Teardown codecs, plus existing local single-link AP/STA execution. MAC negotiation, automatic TSF mapping, optional/broadcast/protected codecs, MLO/EMLSR, OFDMA, energy validation and full-frame SP containment remain unsupported. The earlier MLO regression remains unresolved; see doc/twt/REGRESSION_STATUS.md.