Local unannounced AP/STA TWT executor checkpoint on ns-3.48 Local acceptance: 59 test cases and both physical probes passed. AP DL probe recorded 1261 DATA PSDU starts inside SPs and zero outside across two TWT STAs, alongside an ordinary active STA. Scope: local unannounced unicast execution on one associated QoS link. Wire negotiation, TSF synchronization, complete groupcast, MLO/EMLSR, OFDMA, energy validation and full-frame SP containment remain unsupported. An earlier MLO regression remains unresolved; see doc/twt/REGRESSION_STATUS.md.