fix(grpc): typed alarm-feed overflow, memoized alarm snapshot, cancellable stream writes, uniform reply correlation id

- StreamAlarms: slow subscribers are completed with
  AlarmFeedSubscriberOverflowException and surface as ResourceExhausted
  (like a StreamEvents overflow) instead of warning-with-stack + Unavailable.
- GatewayAlarmMonitor.StreamAsync reuses the memoized alarm-set projection
  instead of cloning the whole set under the broadcast lock per attach; the
  prefix filter runs outside the lock.
- StreamEvents/StreamAlarms pass the call token to response writes; a write
  failure after client cancel maps to Cancelled without a warning.
- Every MxCommandReply.correlation_id now echoes the request's
  client_correlation_id (previously only constraint-denied replies did;
  normal replies leaked the internal envelope id).

src/ZB.MOM.WW.MxGateway.Tests/TestSupport/RecordingServerStreamWriter.cs

@@ -29,6 +29,25 @@ public sealed class RecordingServerStreamWriter<T> : IServerStreamWriter<T>
     /// <summary>Gets or sets options for writing messages to the stream.</summary>
     public WriteOptions? WriteOptions { get; set; }
 
+    /// <summary>Gets the cancellation token passed to the most recent token-bearing write.</summary>
+    public CancellationToken LastWriteCancellationToken { get; private set; }
+
+    /// <summary>Records the supplied message unless the token is already cancelled.</summary>
+    /// <param name="message">The message to record.</param>
+    /// <param name="cancellationToken">Token that cancels the write.</param>
+    /// <returns>A completed task.</returns>
+    /// <remarks>
+    ///     The interface default throws <see cref="NotSupportedException"/> for a cancelable token,
+    ///     and the gateway passes the call's token on every streamed write, so a test writer must
+    ///     override this overload the way the ASP.NET Core writer does.
+    /// </remarks>
+    public Task WriteAsync(T message, CancellationToken cancellationToken)
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        LastWriteCancellationToken = cancellationToken;
+        return WriteAsync(message);
+    }
+
     /// <summary>Records the supplied message.</summary>
     /// <param name="message">The message to record.</param>
     /// <returns>A completed task.</returns>