feat(streaming): carry IsMesReportable on AlarmStateUpdate (25) and DebugAlarmStateDto (20) (ScadaBridge#60)

Central's Debug View live stream and Alarm Summary cache always saw false
because neither wire message had the field. Additive proto fields, vendored
C# regenerated with docker/regen-proto.sh (sitestream + sitecommand), mapped
both ways in StreamRelayActor/SiteStreamGrpcClient and SiteCommandDtoMapper.
The live stream publishes Alarm Actor events, which never carried the flag,
so InstanceActor.HandleAlarmStateChanged now stamps it before retaining and
publishing. A pre-#60 site sends the proto3 default. No UI badge yet.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/StreamRelayActorTests.cs

@@ -209,6 +209,40 @@ public class StreamRelayActorTests : TestKit
                 SiteStreamGrpcClient.ConvertToDomainEvent(unackedProto)).AckTime);
     }
 
+    /// <summary>
+    /// Verifies that the MES-reportable flag survives the relay → proto → central decode
+    /// round trip (Gitea #60, <c>AlarmStateUpdate</c> field 25), and that an unflagged alarm
+    /// arrives as false.
+    /// </summary>
+    [Fact]
+    public void RelaysAlarmStateChanged_IsMesReportable_SurvivesFullRoundTrip()
+    {
+        var channel = Channel.CreateUnbounded<SiteStreamEvent>();
+        var actor = Sys.ActorOf(Props.Create(() =>
+            new StreamRelayActor("corr-mes", channel.Writer)));
+
+        var flagged = new AlarmStateChanged(
+            "Site1.Oven1", "HighTemp", AlarmState.Active, 700,
+            new DateTimeOffset(2026, 11, 9, 12, 0, 0, TimeSpan.Zero))
+        {
+            IsMesReportable = true
+        };
+
+        actor.Tell(flagged);
+        var flaggedProto = ReadProtoEvent(channel);
+        Assert.True(flaggedProto.AlarmChanged.IsMesReportable);
+        Assert.True(
+            Assert.IsType<AlarmStateChanged>(
+                SiteStreamGrpcClient.ConvertToDomainEvent(flaggedProto)).IsMesReportable);
+
+        actor.Tell(flagged with { IsMesReportable = false });
+        var plainProto = ReadProtoEvent(channel);
+        Assert.False(plainProto.AlarmChanged.IsMesReportable);
+        Assert.False(
+            Assert.IsType<AlarmStateChanged>(
+                SiteStreamGrpcClient.ConvertToDomainEvent(plainProto)).IsMesReportable);
+    }
+
     /// <summary>
     /// Reads the next relayed proto event, retrying once after a short pause because the
     /// relay actor writes to the channel asynchronously (mirrors the existing round-trip