feat(otopcua): add ITagDiscovery.RediscoverPolicy + per-driver assignments (follow-up B)

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

@@ -401,6 +401,14 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
 
     // ---- ITagDiscovery ----
 
+    /// <summary>
+    ///     Retry-until-stable: the FixedTree subtree is filled in asynchronously by
+    ///     <see cref="FixedTreeLoopAsync"/> a couple of seconds AFTER connect, so the first
+    ///     post-connect <see cref="DiscoverAsync"/> pass would miss it — the host must re-run
+    ///     discovery until the captured node set is non-empty and stable.
+    /// </summary>
+    public DiscoveryRediscoverPolicy RediscoverPolicy => DiscoveryRediscoverPolicy.UntilStable;
+
     /// <summary>Discovers tags and builds the OPC UA address space asynchronously.</summary>
     /// <param name="builder">The address space builder for constructing the OPC UA namespace.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>