fix(opcua): DeleteRawModified with an unspecified bound is BadInvalidArgument; HistoryUpdate node-manager tests

- A DateTime.MinValue start or end on DeleteRawModified is refused
  BadInvalidArgument before the backend.
- Tests: anonymous without the HistoryUpdate role denied (with it allowed),
  UpdateTagAttributes enabling historization sets HistoryWrite, a throwing
  updater is BadInternalError, the MinValue bounds case; corrected the
  test helper's comment on how the SDK base seeds unadmitted slots.
- GatewayHistorianValueWriter remarks describe the recorder's real status
  capture (and that it does not persist on the gateway).

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

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs

@@ -5295,6 +5295,10 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
             if (details.IsDeleteModified) return null;
             var start = details.StartTime;
             var end = details.EndTime;
+            // Part 11 requires both bounds of a raw delete; DateTime.MinValue is the wire's "unspecified". Refuse
+            // it here rather than let a backend read MinValue as "from the beginning of time".
+            if (start == DateTime.MinValue || end == DateTime.MinValue)
+                return (_, _, _) => Task.FromResult(new HistoryUpdateResult { StatusCode = StatusCodes.BadInvalidArgument });
             return async (updater, tagname, ct) =>
             {
                 var code = await updater.DeleteRawAsync(tagname, start, end, ct).ConfigureAwait(false);