fix(core-abstractions): resolve Low code-review findings (Core.Abstractions-004,005,006,007,008)

- Core.Abstractions-004: guard DriverTypeRegistry.Register with a Lock so
  concurrent registrations are atomic.
- Core.Abstractions-005: narrow PollGroupEngine catch blocks to non-fatal
  exceptions, add optional onError callback, tolerate disposed-CTS races.
- Core.Abstractions-006: document the deliberate int-vs-uint asymmetry on
  IHistoryProvider.ReadEventsAsync / IHistorianDataSource.ReadEventsAsync.
- Core.Abstractions-007: pin the gaps with PollGroupEngine + DriverHealth
  contract tests.
- Core.Abstractions-008: correct XML docs on DriverHealth.LastError and
  the optional / required asymmetry on the history-read surfaces.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/Historian/IHistorianDataSource.cs

@@ -59,6 +59,21 @@ public interface IHistorianDataSource : IDisposable
     ///     Distinct from any live event stream; sources here come from the historian's
     ///     event log. <paramref name="sourceName"/> is null to return all sources.
     /// </summary>
+    /// <remarks>
+    ///     Note on parameter types — <paramref name="maxEvents"/> is <see cref="int"/> (not
+    ///     <see cref="uint"/>) so callers can pass <c>0</c> or a negative value as a "use the
+    ///     backend's default cap" sentinel; see <c>WonderwareHistorianClient</c> /
+    ///     <c>HistorianDataSource</c> and Core.Abstractions-006 for the rationale. The sibling
+    ///     <see cref="ReadRawAsync"/> / <see cref="ReadProcessedAsync"/> use
+    ///     <c>uint maxValuesPerNode</c> because their OPC UA HistoryRead surface has no
+    ///     equivalent "use default" sentinel.
+    ///
+    ///     This surface declares <see cref="ReadAtTimeAsync"/> and <see cref="ReadEventsAsync"/>
+    ///     as required members — a server-side historian owns the full read surface, unlike
+    ///     <see cref="IHistoryProvider"/> where the same two methods are optional default-impl
+    ///     methods so legacy drivers can stay raw-only. The asymmetry is intentional
+    ///     (Core.Abstractions-008).
+    /// </remarks>
     Task<HistoricalEventsResult> ReadEventsAsync(
         string? sourceName,
         DateTime startUtc,