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/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/NativeAlarmProjector.cs

@@ -49,10 +49,13 @@ public sealed class NativeAlarmProjector
     ///         <item>Gitea #656 — <see cref="AlarmTransitionKind.ActiveAcknowledged"/> projects Active+acked in ONE
     ///         update (never an Active+unacked intermediate a client could see) and writes "Activated" only when the
     ///         condition was not already showing that alarm active, then "Acknowledged" only when it was not acked.</item>
+    ///         <item>Gitea #657 — <see cref="AlarmTransitionKind.InactiveUnacknowledged"/> projects inactive+unacked in ONE
+    ///         update and writes "Activated" + "Cleared" only when the condition was acknowledged (an un-ack needs a new
+    ///         occurrence), "Cleared" alone when it was Active+unacked, nothing when it already showed exactly that.</item>
     ///         <item>Gitea #656 — a <see cref="AlarmEventArgs.IsRestatement"/> event (a source re-stating upstream's
     ///         current state: a reconnect snapshot, first sight after a respawn) writes no row when it changes nothing
-    ///         the condition shows: a Retrigger on an Active+unacked condition with the same message AND severity, or
-    ///         a Clear on an already-inactive condition; and a flagged Unspecified update of an already-active
+    ///         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 Acknowledge on an already-acknowledged one (#657); and a flagged Unspecified update of an already-active
     ///         condition moves its message/severity (node + one condition event) with active/acked kept and no row
     ///         (AbCip ALMA's governing-limit change). Unflagged sources (FOCAS, MTConnect, live Galaxy transitions) are
     ///         unaffected — a live Retrigger is a genuine re-occurrence and keeps its row.</item>
@@ -99,6 +102,21 @@ public sealed class NativeAlarmProjector
                     ? [AlarmTransitionKind.Raise, AlarmTransitionKind.Acknowledge]
                     : !prev.Acked ? [AlarmTransitionKind.Acknowledge] : [];
                 break;
+            // #657: the mirror of ActiveAcknowledged — inactive AND unacked in ONE update (never Raise-then-Clear, which
+            // showed clients the condition Active again for an instant). Rows only for what changed: an acknowledged
+            // condition can only have become unacked through a new occurrence ("Activated" + "Cleared"); an
+            // Active+unacked one just cleared; one already inactive+unacked changed nothing.
+            case AlarmTransitionKind.InactiveUnacknowledged:
+                (active, acked) = (false, false);
+                historyKinds = prev.Acked
+                    ? [AlarmTransitionKind.Raise, AlarmTransitionKind.Clear]
+                    : prev.Active ? [AlarmTransitionKind.Clear] : [];
+                break;
+            // #657: a source re-stating an acknowledgement the condition already shows (OpcUaClient's first sight of
+            // an inactive+acked condition is a flagged Clear + Acknowledge) changes nothing.
+            case AlarmTransitionKind.Acknowledge when e.IsRestatement && prev.Acked:
+                (active, acked, historyKinds) = (prev.Active, true, []);
+                break;
             case AlarmTransitionKind.Acknowledge:
                 (active, acked, historyKinds) = (prev.Active, true, [AlarmTransitionKind.Acknowledge]);
                 break;
@@ -112,9 +130,8 @@ public sealed class NativeAlarmProjector
                 break;
             // A message/severity-only update of an ALREADY-ACTIVE condition that the source flags as a re-statement
             // (AbCip ALMA: the governing limit changed but no new occurrence started, e.g. HH dropped back to H).
-            // OpcUaClient can reach it too: first sight after a respawn of an upstream-inactive condition is told
-            // Unspecified+flagged; with the host still Active the node stays Active exactly as before (a pre-existing
-            // gap) and the false "Activated" row it used to write is now gone.
+            // OpcUaClient no longer reaches it (#657: its first sight of an inactive condition is a flagged Clear +
+            // Acknowledge, or an InactiveUnacknowledged — never a flagged Unspecified).
             // The node's text/severity move; active/acked are kept; NO row (an "Activated" row would be false).
             case AlarmTransitionKind.Unspecified when e.IsRestatement && prev.Active:
                 (active, acked, historyKinds) = (true, prev.Acked, []);