fix(server): enforce published HistoryUpdate operation limits

[MrAlaskan]

Summary

This PR enforces the published HistoryUpdate operation limits in the server service entry point and adds regression coverage that verifies requests exceeding MaxNodesPerHistoryUpdateData or MaxNodesPerHistoryUpdateEvents are rejected with BadTooManyOperations.

Problem

The server already publishes MaxNodesPerHistoryUpdateData and MaxNodesPerHistoryUpdateEvents through ServerCapabilities.OperationLimits, but StandardServer.HistoryUpdateAsync() did not actually enforce either limit. The method only called the generic ValidateOperationLimits(historyUpdateDetails) overload without passing a concrete limit, which meant it only rejected empty requests with BadNothingToDo and never returned BadTooManyOperations for oversized HistoryUpdate requests.

The existing code already acknowledged this gap: HistoryUpdateAsync() contained a TODO comment stating that the history-update operation limits still needed to be checked elsewhere. In practice, neither StandardServer, MasterNodeManager, nor the downstream node-manager paths consumed MaxNodesPerHistoryUpdateData or MaxNodesPerHistoryUpdateEvents, so the advertised limits were never enforced at runtime.

Changes

• Enforce HistoryUpdate operation limits in StandardServer.HistoryUpdateAsync() after the existing non-empty request validation.
• Classify HistoryUpdateDetails into data-oriented vs event-oriented requests and apply MaxNodesPerHistoryUpdateData or MaxNodesPerHistoryUpdateEvents accordingly.
• Add integration-style regression tests that verify oversized data-update and event-update requests are both rejected with BadTooManyOperations.

[marcschier]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[codecov]

Codecov Report

❌ Patch coverage is 84.61538% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.12%. Comparing base (84fa8e8) to head (8cd7f20).
⚠️ Report is 18 commits behind head on master.

Files with missing lines	Patch %	Lines
src/Opc.Ua.Server/Server/StandardServer.cs	84.61%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4034      +/-   ##
==========================================
- Coverage   73.85%   73.12%   -0.74%     
==========================================
  Files        1345     1332      -13     
  Lines      179988   179102     -886     
  Branches    31668    31540     -128     
==========================================
- Hits       132938   130973    -1965     
- Misses      36299    37496    +1197     
+ Partials    10751    10633     -118     

Files with missing lines	Coverage Δ
src/Opc.Ua.Server/Server/StandardServer.cs	73.49% <84.61%> (+0.09%)	⬆️

... and 91 files with indirect coverage changes

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