fix(mqtt): birth-typed Sparkplug writes and QoS 1 for Plain writes (#602 STAB-25/26)

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

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Mqtt/MqttDriver.cs

@@ -544,6 +544,11 @@ public sealed class MqttDriver
     /// </summary>
     /// <remarks>
     ///     <para>
+    ///         <b>Also the write path's type (STAB-25).</b> <see cref="WriteAsync"/> encodes a Sparkplug
+    ///         command with this same answer, so a birth-typed Int32 metric is commanded as Int32 rather than
+    ///         as the record's default.
+    ///     </para>
+    ///     <para>
     ///         <b>The precedence is the ingest path's, restated.</b> <c>SparkplugIngestor.PublishMetric</c>
     ///         coerces every value with <c>DataTypeAuthored ? authored : birth</c>; a discovery surface
     ///         that disagreed with it would advertise a type no value ever arrives as. The two must be
@@ -674,7 +679,10 @@ public sealed class MqttDriver
     ///     reference reject every other write in the same OPC UA request.
     ///     </para>
     ///     <para>
-    ///     <b>Good means "published", not "applied".</b> MQTT has no application-level write
+    ///     <b>Good means "published", not "applied".</b> A Plain-mode write is published at QoS 1
+    ///     (STAB-26), so "published" means the broker PUBACKed it — a broker-side refusal or a drop under
+    ///     the send is Bad, not Good. Sparkplug NCMD/DCMD stay at QoS 0 (a redelivered command would be
+    ///     re-applied). MQTT has no application-level write
     ///     acknowledgement, so a successful PUBLISH is the strongest truth available at this seam —
     ///     the same optimistic-Good posture Galaxy's fire-and-forget write takes. Device-level truth
     ///     arrives afterwards, as the echoed value on the tag's read topic, and corrects the node
@@ -709,7 +717,8 @@ public sealed class MqttDriver
                 continue;
             }
 
-            var error = MqttWriteEncoder.TryEncode(_options.Mode, def, w.Value, out var encoded);
+            var error = MqttWriteEncoder.TryEncode(
+                _options.Mode, def, w.Value, out var encoded, ResolveDiscoveredDataType(def));
             if (error != MqttWriteEncodeError.None)
             {
                 results[i] = new WriteResult(MapEncodeError(error));
@@ -728,7 +737,7 @@ public sealed class MqttDriver
             try
             {
                 await connection
-                    .PublishAsync(encoded.Topic, encoded.Payload, MqttWriteEncoder.WriteQos, retain: false, cancellationToken)
+                    .PublishAsync(encoded.Topic, encoded.Payload, encoded.Qos, retain: false, cancellationToken)
                     .ConfigureAwait(false);
                 results[i] = new WriteResult(0u);
             }