SetSignature refuses Emission; Sensor.PingVisibility (key 7) is retired and
Ping() writes no signature; Sense's Emission skip, the departure subtraction
and SignatureOn are deleted. Tests: SetSignatureRefusesEmission,
APingNoLongerBrightensThePinger; fixtures drop PingVisibility.
Not yet built or tested at this commit (verify job follows).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
d8b7f33d90