Ready Release

[barnett]

Fixes

Prepare the .NET SDK repository for release validation without publishing.

Summary

• Restore and build the full solution in CI.
• Make test discovery mandatory so compile/test setup failures are visible.
• Run integration tests only when Trolley API credentials are configured, and fail CI if they fail.
• Align 2.2.4 package metadata and include README.md in the NuGet package.
• Remove tracked build/IDE artifacts already covered by .gitignore.

Test plan

• dotnet restore trolley.sln
• dotnet build trolley.sln --configuration Release --no-restore
• dotnet pack trolley/trolley.csproj --configuration Release --no-build --output /tmp/dotnet-pack-readiness
• dotnet test tests/tests.sln --configuration Release --no-build --list-tests
• unzip -l /tmp/dotnet-pack-readiness/trolleyhq.2.2.4.nupkg | rg 'README|lib/'
• Workflow YAML parse check
• CircleCI passed on pushed branch

Notes

This PR does not publish 2.2.4; it only addresses release-readiness blockers before publishing.

[heyflowmo]

looks good