fix(alarms): atomic InactiveUnacknowledged + flagged Clear/Acknowledge first sight for OpcUaClient (#657)

After an OpcUaClient respawn an upstream inactive+unacked condition went out as
Retrigger+Clear (duplicate Activated+Cleared rows, Active flicker), and a
first-sight inactive+acked one as Unspecified (an Activated row for an inactive
alarm; a retained-Active host condition never cleared).

- New AlarmTransitionKind.InactiveUnacknowledged: one projection, rows only for
  what changed (Activated+Cleared from acked, Cleared from active+unacked, none
  when already inactive+unacked).
- OpcUaClient uses it for moves into inactive+unacked; first sight of an
  inactive condition is InactiveUnacknowledged or Clear+Acknowledge, flagged.
- Projector: a flagged Acknowledge on an already-acked condition writes no row.
- E2E tests through DriverHostActor.ForwardNativeAlarm (red-proven).

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IAlarmSource.cs

@@ -107,11 +107,13 @@ public sealed record AlarmAcknowledgeRequest(
 ///     watched happen: a reconnect snapshot entry (Galaxy) or the first event for a condition after a driver start or
 ///     deploy respawn (OpcUaClient). It governs <b>history only, never node state</b>: the host still projects the
 ///     state, but writes no <c>alerts</c> row when the re-statement changes nothing the condition shows (a Retrigger on
-///     an Active+unacked condition with the same message and severity; a Clear on an already-inactive condition) — or
+///     an Active+unacked condition with the same message and severity; a Clear on an already-inactive condition; an
+///     Acknowledge on an already-acknowledged condition) — or
 ///     when a flagged <see cref="AlarmTransitionKind.Unspecified"/> update moves the message/severity of an
 ///     already-active condition (node updated, one condition event, active/acked kept, no row). AbCip ALMA sets the
-///     flag for the last shape (the governing limit changed, no new occurrence); OpcUaClient's first sight of an
-///     inactive condition after a respawn can reach it too. <c>false</c> (the default, every source that does not
+///     flag for the last shape (the governing limit changed, no new occurrence). OpcUaClient (Gitea #657) re-states a
+///     first-seen inactive+acked condition as a flagged Clear then a flagged Acknowledge, so a host already showing
+///     that writes nothing and a host retaining it Active gets a real "Cleared". <c>false</c> (the default, every source that does not
 ///     opt in) keeps every transition's row.
 /// </param>
 public sealed record AlarmEventArgs(
@@ -147,6 +149,11 @@ public enum AlarmSeverity { Low, Medium, High, Critical }
 ///     transition-kind enums (e.g. Galaxy's <c>GalaxyAlarmTransitionKind</c>).
 ///     <see cref="ActiveAcknowledged"/> (Gitea #656) means "the condition is active AND acknowledged", applied by the
 ///     host as ONE projection — never Raise-then-Acknowledge, which would show clients an Active+unacked intermediate.
+///     <see cref="InactiveUnacknowledged"/> (Gitea #657) is its mirror: "the condition is inactive AND unacknowledged"
+///     (it went active and cleared unacknowledged), applied as ONE projection — never Raise-then-Clear, which showed
+///     clients the condition Active again for an instant. The host writes rows only for what actually changed:
+///     "Activated" + "Cleared" when the condition was acknowledged (a new occurrence must have happened), "Cleared"
+///     alone when it was Active+unacked, none when it already showed inactive+unacked.
 ///     Members are append-only: their numeric values must not move.
 /// </summary>
-public enum AlarmTransitionKind { Unspecified = 0, Raise, Acknowledge, Clear, Retrigger, ActiveAcknowledged }
+public enum AlarmTransitionKind { Unspecified = 0, Raise, Acknowledge, Clear, Retrigger, ActiveAcknowledged, InactiveUnacknowledged }