Review 07 H13: _devices and _tagsByRawPath were plain dictionaries cleared and
refilled in place while the retained poll loop, the actor's GetHostStatuses and
server reads enumerated them. Both are now built locally and published by
reference under a lifecycle lock; teardown swaps in empty tables.
Lane A contract: ShutdownAsync and Dispose each retire a disjoint set of device
states, so Dispose running concurrently with a still-joining ShutdownAsync is
safe. A lifecycle epoch makes an InitializeAsync that the runtime abandoned
(overlapping the next ShutdownAsync) refuse to publish its tables, start probe
loops or write health. A runtime cached on an already-retired device state by an
in-flight read is disposed instead of leaked, and late reads/writes no longer
overwrite shutdown's health. Per-key semaphores are no longer disposed under
callers that may still hold them.
Refs #738
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Joseph Doherty
92171a01ec