[Server] Make SubscriptionManagement Methods Async & Fix Publishing of GoodSubscriptionTransferred Message

[romanett]

Proposed changes

• Obsolete all sync methods in the server
• Update SubscriptionManager to use SemaphoreSlim
• Remove Sync overloads from MasterNodeManager
• Fix SessionPublishQueue to allow publishing Custom Status Messages for Good Status Codes

Related Issues

• Fixes #

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Enhancement (non-breaking change which adds functionality)
• Test enhancement (non-breaking change to increase test coverage)
• Breaking change (fix or feature that would cause existing functionality to not work as expected, requires version increase of Nuget packages)
• Documentation Update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc.
• I have signed the CLA.
• I ran tests locally with my changes, all passed.
• I fixed all failing tests in the CI pipelines.
• I fixed all introduced issues with CodeQL and LGTM.
• I have added tests that prove my fix is effective or that my feature works and increased code coverage.
• I have added necessary documentation (if appropriate).
• Any dependent changes have been merged and published in downstream modules.

[codecov]

Codecov Report

❌ Patch coverage is 84.05797% with 33 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.00%. Comparing base (d25caff) to head (ee83d91).
⚠️ Report is 10 commits behind head on master.

Files with missing lines	Patch %	Lines
Libraries/Opc.Ua.Server/Server/StandardServer.cs	84.87%	18 Missing ⚠️
.../Opc.Ua.Server/Subscription/SubscriptionManager.cs	88.88%	6 Missing and 1 partial ⚠️
...braries/Opc.Ua.Server/Subscription/Subscription.cs	70.00%	6 Missing ⚠️
.../Opc.Ua.Server/Subscription/SessionPublishQueue.cs	33.33%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3350      +/-   ##
==========================================
+ Coverage   51.86%   60.00%   +8.14%     
==========================================
  Files         370      371       +1     
  Lines       78618    78217     -401     
  Branches    13650    13600      -50     
==========================================
+ Hits        40779    46938    +6159     
+ Misses      33705    26976    -6729     
- Partials     4134     4303     +169     

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[Copilot]

Pull Request Overview

This PR modernizes the OPC UA .NET Standard Server subscription management by converting synchronous methods to async/await patterns and replacing Lock with SemaphoreSlim for better async compatibility. The changes enable proper async operation throughout the subscription lifecycle while fixing a bug that prevented publishing Good status codes for subscription transfer notifications.

Key Changes:

• Replaced Lock with SemaphoreSlim in SubscriptionManager for async-compatible synchronization
• Converted subscription lifecycle methods (StartupAsync, ShutdownAsync, RestoreSubscriptionsAsync, etc.) to async
• Removed synchronous wrapper methods from MasterNodeManager that used blocking calls on async methods
• Fixed SessionPublishQueue.TryPublishCustomStatus to properly handle Good status codes by returning null subscription instead of throwing an exception

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
Stack/Opc.Ua.Core/Opc.Ua.Core.csproj	Removed OPCUA_EXCLUDE flags to enable async methods for subscription-related operations
Tests/Opc.Ua.Server.Tests/ServerTestServices.cs	Updated test service methods to call async server methods directly instead of using sync wrappers
Libraries/Opc.Ua.Server/Subscription/SubscriptionManager.cs	Replaced Lock with SemaphoreSlim; converted lifecycle methods to async; updated synchronization patterns
Libraries/Opc.Ua.Server/Subscription/Subscription.cs	Added RestoreAsync factory method; converted ConditionRefresh and SetMonitoringMode methods to async
Libraries/Opc.Ua.Server/Subscription/SessionPublishQueue.cs	Fixed TryPublishCustomStatus to handle Good status codes by returning null instead of throwing
Libraries/Opc.Ua.Server/Subscription/ISubscriptionManager.cs	Updated interface signatures to async methods
Libraries/Opc.Ua.Server/Subscription/ISubscription.cs	Updated interface signatures to async methods
Libraries/Opc.Ua.Server/Server/StandardServer.cs	Converted subscription and node management methods to async; updated to return response objects directly
Libraries/Opc.Ua.Server/NodeManager/MasterNodeManager.cs	Removed sync wrapper methods; added cancellation token parameter to ShutdownAsync