clockOffset property

Seconds to add to sourceClock to map it into the local clock domain.

LSL: lsl_time_correction(), refreshed periodically per inlet. In-memory: zero, since both ends share a process and therefore a clock. WebSocket and WebRTC: the coordination layer's own estimate (ClockSyncService), and null until the first one has been made.

Null means "not known", which is distinct from a known offset of zero.