865beb82d5
P6 claimed acmd/ecmd/usbaudiod were 32-line stubs; P1-D (2026-07-08) resolved that they are real implementations. Verified 2026-07-20: redbear-acmd 186 LoC (line coding, DTR/RTS, scheme), redbear-ecmd 314, redbear-usbaudiod 367. P6-A remaining scope is CTS/DSR flow control, break signaling, and multi-port modem support; NCM/audio/serial-chip families remain missing entirely.