R02:P1: SqlDriver runs PollGroupEngine, so it now implements IBatchSubscribable and
raises one OnDataChangeBatch per poll burst (DriverInstanceActor forwards one message
per cycle instead of one per tag).
S-9: InitializeAsync/ShutdownAsync take a lifecycle generation; their health writes
apply only while current, and a poll that started under an older generation (one that
outlived the engine's teardown wait) no longer writes its verdict onto the new
configuration. Poll-driven updates can no longer end Initializing - only the
initialize's own final write does. Lifecycle writes now preserve LastSuccessfulRead.
Refs #744
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Joseph Doherty
a7d21d5a65