fix(drivers): ResolveHost resolves equipment-tag refs via EquipmentTagRefResolver — per-host breaker isolation (CONV-4)

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FocasDriver.cs

@@ -1114,10 +1114,20 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
 
     // ---- IPerCallHostResolver ----
 
-    /// <inheritdoc />
+    /// <summary>
+    ///     Resolve a reference to the device host that keys its per-host resilience
+    ///     (bulkhead / circuit breaker). CONV-4: routes through
+    ///     <see cref="EquipmentTagRefResolver{TDef}"/> so an equipment-tag reference (raw TagConfig
+    ///     JSON) resolves to its OWN authored device rather than the first-device fallback. The
+    ///     empty-host guard covers FOCAS's <c>?? ""</c> default so an address-less equipment tag
+    ///     falls back rather than keying an empty host. The resolver caches parses, so this adds no
+    ///     per-call cost after first use.
+    /// </summary>
+    /// <param name="fullReference">The tag reference (authored name or equipment-tag JSON).</param>
+    /// <returns>The device host key.</returns>
     public string ResolveHost(string fullReference)
     {
-        if (_tagsByName.TryGetValue(fullReference, out var def))
+        if (_resolver.TryResolve(fullReference, out var def) && !string.IsNullOrEmpty(def.DeviceHostAddress))
             return def.DeviceHostAddress;
         return _options.Devices.FirstOrDefault()?.HostAddress ?? DriverInstanceId;
     }