Adds the six E116-0712 §6.2 buckets for classifying equipment time:
NonScheduledTime (0) not scheduled to operate
ScheduledDowntime (1) planned maintenance window
UnscheduledDowntime (2) faults / unplanned stoppage
Engineering (3) engineering / qualification time
Standby (4) idle but available
Productive (5) actively producing
Wire-byte values pinned via static_assert to E116 §10.3.
The FSM is a classifier rather than a strict lifecycle — every
(state, event) pair is legal — but it remains data-driven through the
shared CarrierTransitionTable template so the default cross-product is
expressible declaratively.
The state-change handler also surfaces dwell time (how long the
previous state was held) computed off std::chrono::steady_clock, so
accounting code can compute MTBF / availability / utilization from a
single source without maintaining a parallel timestamp log.
4 test cases cover the initial state, every event firing, dwell-time
reporting, and the no-op same-state event (no handler call).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
