fix(opcuaclient): #676 review fix-ups (port-less rewrite, full reconcile, delivery lock, timers)

1. RewriteEndpointUrl keeps the advertised port when the configured URL names none
   (Uri.Port -1 would have sent the session to 4840); port-less + IPv6 tests.
2. The trailing re-read repairs any (value, status) difference that is not older than
   the last delivered value — Good->Bad/Uncertain included; a read without a source
   timestamp counts as newer; an equal source time with different content is published
   (repairs the replay guard's by-design equal-timestamp drop).
3. One driver-wide delivery lock makes decide+publish atomic across live notifications,
   the recovery read and the trailing read, so an older value can never land after a
   newer one (deterministic race test via a seam).
4. Known gap documented: a ConnectionLost raised while the host is not Connected is
   swallowed and that session falls back to the watchdog.
5. Only a SERVER-reported subscription loss raises ConnectionLost; the publishing-stall
   heuristic stays with the #527 watchdog.
6. Post-recovery timers run on Task.Delay(…, Clock, ct) with a session-work CTS
   cancelled on session release and dispose.
7. Replay summary at Information only when something was dropped (Debug otherwise);
   a re-arm reports the superseded window's drops and counts afresh.
8. DriverInstanceActor: AttachHostStatusSource doc comment restored; Reconnecting
   swallows a stray DisconnectObserved (test).
9. Stall wire test: 120 s session timeout, 3000-cycle subscription lifetime, one further
   bad keep-alive tick, 60 s headroom on the post-recovery waits (5/5 green).

docs/DriverLifecycle.md

@@ -458,13 +458,18 @@ alternatives:
   communication" — must not raise: a stalled link that resumes keeps its session, subscriptions and in-place recovery,
   and tearing it down would cost all three. Those stay with the watchdog, whose conjunction is the honest test for them.
 - **Today only `OpcUaClientDriver` implements it:** keep-alive `BadSessionIdInvalid` / `BadSessionClosed` /
-  `BadSessionNotActivated` / `BadServerHalted`, or a subscription the server dropped (see
+  `BadSessionNotActivated` / `BadServerHalted`, or a subscription the server REPORTED dropped (not the driver's
+  publishing-stall heuristic, which is an inference from silence and stays with the watchdog; see
   [OpcUaClient.md](drivers/OpcUaClient.md) §"Upstream outage and recovery" for why `BadServerHalted` is on the list —
   it was measured, the SDK never re-opens a halted channel). A gracefully restarted upstream therefore recovers in
   about one reconnect interval instead of ~100 s; a killed one still waits for the watchdog.
+- ⚠️ **Known gap:** "only while `Connected`" plus "once per connection" means a raise the host receives while not yet
+  Connected (e.g. the protocol proves the fresh connection dead before `InitializeSucceeded` is processed) is swallowed,
+  and that connection falls back to the watchdog — the pre-#676 recovery time, in a narrow window.
 - Pinned by `DriverInstanceActorConnectionLossSignalTests` (Reconnecting within seconds while the watchdog is set to an
-  hour; a falsification control with no raise that stays Connected; a raise mid-connect ignored; detach on stop) and
-  `OpcUaClientConnectionLossSignalTests` (definitive raises once, ambiguous never, re-armed after re-init).
+  hour; a falsification control with no raise that stays Connected; a raise mid-connect ignored; a stray watchdog
+  `DisconnectObserved` in `Reconnecting` is a no-op; detach on stop) and `OpcUaClientConnectionLossSignalTests`
+  (definitive raises once, ambiguous and the stall heuristic never, re-armed after re-init).
 
 **The reconnect retry now tears down before re-initialising.** `Reconnecting`'s `RetryConnect` calls
 `ShutdownAsync` before `InitializeAsync` — the sequence every driver's own `ReinitializeAsync` already