Adds the substrate-ID verification FSM that E90 §6.4.6 calls for:
NotConfirmed initial; equipment hasn't read the ID yet
WaitingForHost ID has been read; awaiting host accept/reject
Confirmed host confirmed (or force-bound)
Mismatched host rejected — recoverable via Bind
Events:
Read NotConfirmed -> WaitingForHost
Confirm WaitingForHost -> Confirmed
Mismatch WaitingForHost -> Mismatched
Bind any -> Confirmed (force-bind)
Reset any -> NotConfirmed
Wire-byte values pinned via static_assert. The third axis is now
exposed on SubstrateStateMachine alongside location_state() and
processing_state(); set_id_handler() observes transitions. Existing
two-axis API is unchanged.
4 new test cases cover the happy path, Mismatch+Bind recovery, Reset
from any state, and same-state event handler suppression.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>