feat(twincat): opt-in ADS sum-read and /hosts diagnostics bag; refresh TwinCAT backlog (#645, #612)

Sum-read (#310): batches a poll's reads per device into sum commands capped at sumReadMaxItems,
per-item ADS errors mapped per tag, falls back to individual reads when the target refuses the
command. Diagnostics (#314): ADS state, app name, online-change count, task cycle/exec/jitter via
IDriverDiagnostics. Re-implemented against the current raw-byte read path (stranded auto/driver-gaps
commits predate it). Sum-write not ported. Unit tests only; live gate pending a route.

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

tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/TwinCATDriverPageFormSerializationTests.cs

@@ -72,6 +72,8 @@ public sealed class TwinCATDriverPageFormSerializationTests
             UseNativeNotifications = true,
             EnableControllerBrowse = false,
             NotificationMaxDelayMs = 100,
+            UseSumRead = true,
+            SumReadMaxItems = 64,
             Probe = new TwinCATProbeOptions
             {
                 Enabled = true,
@@ -88,6 +90,8 @@ public sealed class TwinCATDriverPageFormSerializationTests
         roundTripped.UseNativeNotifications.ShouldBeTrue();
         roundTripped.EnableControllerBrowse.ShouldBeFalse();
         roundTripped.NotificationMaxDelayMs.ShouldBe(100);
+        roundTripped.UseSumRead.ShouldBeTrue();
+        roundTripped.SumReadMaxItems.ShouldBe(64);
         roundTripped.Probe.Enabled.ShouldBeTrue();
         roundTripped.Probe.Interval.ShouldBe(TimeSpan.FromSeconds(6));
         roundTripped.Probe.Timeout.ShouldBe(TimeSpan.FromSeconds(2));