feat(messages): add DriverHealthChanged DPS contract

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Messages/Drivers/DriverHealthChanged.cs

@@ -0,0 +1,23 @@
+namespace ZB.MOM.WW.OtOpcUa.Commons.Messages.Drivers;
+
+/// <summary>
+///     Snapshot of a single driver instance's health, published to the
+///     <c>driver-health</c> DistributedPubSub topic whenever a driver actor
+///     transitions state or logs an error. Consumed by
+///     <c>DriverStatusSignalRBridge</c> in the AdminUI for live status push.
+/// </summary>
+/// <param name="ClusterId">Cluster this driver belongs to.</param>
+/// <param name="DriverInstanceId">Globally-unique driver instance ID.</param>
+/// <param name="State">DriverState enum as string (Healthy, Faulted, Reconnecting, etc.).</param>
+/// <param name="LastSuccessfulReadUtc">Most recent successful equipment read; null if never.</param>
+/// <param name="LastError">Latest error message; null when none.</param>
+/// <param name="ErrorCount5Min">Number of state-transitions into Faulted in the last 5 minutes.</param>
+/// <param name="PublishedUtc">Timestamp this snapshot was published.</param>
+public sealed record DriverHealthChanged(
+    string ClusterId,
+    string DriverInstanceId,
+    string State,
+    DateTime? LastSuccessfulReadUtc,
+    string? LastError,
+    int ErrorCount5Min,
+    DateTime PublishedUtc);