fix(adminui): AB forms read/write the factory-bound *Ms duration keys, migrate legacy TimeSpan strings (#576)

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

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DriverConfigMs.cs

@@ -0,0 +1,39 @@
+using System.Text.Json;
+using System.Text.Json.Nodes;
+
+namespace ZB.MOM.WW.OtOpcUa.AdminUI.Components.Shared.Drivers;
+
+/// <summary>
+///     Shared millisecond helpers for the AB forms (#576): the driver factories bind <c>*Ms</c> integers
+///     while the forms edit whole seconds, so a sub-second stored value must survive an edit of an
+///     unrelated field.
+/// </summary>
+internal static class DriverConfigMs
+{
+    /// <summary>Reads an integer-millisecond key at <paramref name="path"/> from <paramref name="json"/>, or null.</summary>
+    public static int? Read(string? json, string path)
+    {
+        if (string.IsNullOrWhiteSpace(json)) return null;
+        try
+        {
+            JsonNode? cur = JsonNode.Parse(json);
+            foreach (var seg in path.Split('.'))
+            {
+                if (cur is not JsonObject o) return null;
+                cur = o.FirstOrDefault(kv => string.Equals(kv.Key, seg, StringComparison.OrdinalIgnoreCase)).Value;
+            }
+            return cur is JsonValue v && v.TryGetValue<int>(out var ms) ? ms : null;
+        }
+        catch (JsonException) { return null; }
+    }
+
+    /// <summary>Whole seconds for display (truncating, like the pre-#576 forms).</summary>
+    public static int ToSeconds(TimeSpan t) => (int)t.TotalSeconds;
+
+    /// <summary>
+    ///     The duration to save: the loaded value when the operator left the seconds field unchanged
+    ///     (keeps 500 ms from collapsing to 0 s), else the edited whole seconds.
+    /// </summary>
+    public static TimeSpan Save(int seconds, TimeSpan? loaded)
+        => loaded is { } l && ToSeconds(l) == seconds ? l : TimeSpan.FromSeconds(seconds);
+}