fix(template-engine): carry IsMesReportable onto derived-template placeholder alarms and through descendant reconcile; final-review doc fixes

Claude-Session: https://claude.ai/code/session_01Y5ef34iUUMjmwnMpL9xgmB

tests/ZB.MOM.WW.ScadaBridge.Commons.Tests/Messages/CompatibilityTests.cs

@@ -285,6 +285,29 @@ public class CompatibilityTests
         Assert.Null(deserialized!.AckTime);
     }
 
+    [Fact]
+    public void BackwardCompat_AlarmStateChanged_MissingIsMesReportable_DefaultsToFalse()
+    {
+        // A frame minted by a node predating the MES-reportable flag omits the property
+        // entirely; it must deserialize to "not reported to MES", not fail. False is the
+        // safe default — an old site's alarms stay out of the MES alarm-status API until
+        // it is upgraded and stamps the flag itself.
+        var json = """
+            {
+                "InstanceUniqueName": "inst-1",
+                "AlarmName": "Tank01.Level.HiHi",
+                "State": 1,
+                "Priority": 900,
+                "Timestamp": "2026-08-01T00:00:00+00:00"
+            }
+            """;
+
+        var deserialized = JsonSerializer.Deserialize<AlarmStateChanged>(json, Options);
+
+        Assert.NotNull(deserialized);
+        Assert.False(deserialized!.IsMesReportable);
+    }
+
     [Fact]
     public void RoundTrip_HeartbeatMessage_Succeeds()
     {