fix(uns): reject equipment bind to non-existent driver + modal-xl (review)

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Uns/EquipmentModal.razor

@@ -12,7 +12,7 @@
 {
     <div class="modal-backdrop fade show" style="display:block"></div>
     <div class="modal fade show" tabindex="-1" role="dialog" style="display:block">
-        <div class="modal-dialog modal-lg" role="document">
+        <div class="modal-dialog modal-xl" role="document">
             <div class="modal-content">
                 <EditForm Model="_form" OnValidSubmit="SaveAsync" FormName="equipmentModal">
                     <DataAnnotationsValidator />

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/UnsTreeService.cs

@@ -999,7 +999,12 @@ public sealed class UnsTreeService(IDbContextFactory<OtOpcUaConfigDbContext> dbF
             .Select(d => d.ClusterId)
             .FirstOrDefaultAsync(ct);
 
-        if (driverCluster is not null && driverCluster != lineCluster)
+        if (driverCluster is null)
+        {
+            return new UnsMutationResult(false, $"Driver '{input.DriverInstanceId}' not found.");
+        }
+
+        if (driverCluster != lineCluster)
         {
             return new UnsMutationResult(
                 false,