Add Sample Projects Overview to README and fix CI build pipeline

[Copilot]

Users had no quick way to identify which sample project matched their use case (e.g., already have an external OPC UA server running and just need a client). Additionally, the "Build Solutions" CI job was failing due to a NuGetCommand@2 restore limitation with OS-conditional MSBuild properties.

Proposed changes

• README.md: Added a new ## Sample Projects Overview section with two scannable tables:

  • Core Samples (Samples/) — ReferenceServer, ReferenceClient, UA Sample Server/Client (.NET 4.6), GDS Server/Client variants; each row has project link, Server/Client type badge, and a one-line description of purpose
  • Quickstart Workshop Samples (Workshop/) — all 25 workshop projects (Aggregation, AlarmCondition, Boiler, DataAccess, DataTypes, HistoricalAccess, HistoricalEvents, Methods, PerfTest, SimpleEvents, UserAuthentication, Views, Empty) with the same format
  • Added a callout block directly addressing the common case: if you already have an external OPC UA server (e.g. KepServerEX), skip the server samples and point ReferenceClient at your endpoint

• .azurepipelines/sln.yml: Fixed the "Build Solutions" CI job failure by replacing NuGetCommand@2 command: restore (classic nuget.exe CLI) with MSBuild@1 /t:Restore /p:RestoreForceEvaluate=true. The classic nuget.exe CLI does not reliably evaluate OS-conditional MSBuild properties (specifically $([MSBuild]::IsOsPlatform('Windows')) in targets.props), causing Opc.Ua.Sample.csproj to be resolved without its net48 target framework, making it incompatible with the net48-targeting Client.Net4 and Server.Net4 projects (NU1201). Using MSBuild's native restore target ensures all property imports are correctly evaluated. The now-unused NuGetToolInstaller@1 step was also removed.

Related Issues

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.

Further comments

Table entries were verified against actual directories in the repo; references to NetCoreConsoleServer/NetCoreConsoleClient (present in existing README prose but no longer in the repo) were intentionally excluded from the new tables.

The CI fix uses MSBuild@1 /t:Restore instead of NuGetCommand@2 command: restore because MSBuild's restore target fully evaluates all MSBuild property imports — including the OS-conditional DotNetTargetFramework property that adds net48; to LibTargetFrameworks on Windows — whereas classic nuget.exe restore may not evaluate these conditions consistently across tool versions.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add some brief to each project</issue_title>
<issue_description> Add some descriptions to sample projects,so can quick find the project you need.
Like I have open KepServer as a UPCUA server,don't need to open a server again. which project should I run?</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add some brief to each project #683

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[romanett]

@copilot please fix the build Pipelines so CI passes

[Copilot]

@copilot please fix the build Pipelines so CI passes

Fixed in commit 178878d.

The "Build Solutions" job was failing because NuGetCommand@2 command: restore (classic nuget.exe CLI) does not reliably evaluate OS-conditional MSBuild properties — specifically $([MSBuild]::IsOsPlatform('Windows')) in targets.props. This caused Opc.Ua.Sample.csproj to be seen as only targeting netstandard2.1;net8.0;net10.0 (missing net48), making it incompatible with the net48-targeting Client.Net4 and Server.Net4 projects and producing NU1201.

The fix replaces both NuGetCommand@2 command: restore steps in .azurepipelines/sln.yml with MSBuild@1 /t:Restore /p:RestoreForceEvaluate=true, which uses MSBuild's native restore target and correctly evaluates all MSBuild property imports including OS-conditional ones. The now-unused NuGetToolInstaller@1 step was also removed.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• crl.entrust.net
  • Triggering command: /usr/bin/dotnet dotnet build UA Sample Applications.sln --configuration Release (dns block)
• ocsp.entrust.net
  • Triggering command: /usr/bin/dotnet dotnet build UA Sample Applications.sln --configuration Release (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)