Five tasks: scaffold csproj, copy WakewordModel + models with Reset(),
write Program.cs with the four-state machine, write bin/probe-cs-3
deploy script, and hardware verification on the Pi.
State machine on a single persistent input stream: IDLE → BEEPING →
RECORDING → PLAYBACK → IDLE. Detector gated during non-IDLE states;
WakewordModel.Reset() called on IDLE re-entry to clear stale ring
buffers and re-arm the warmup guard.
tes