Add package dry-run review

[Courtland9777]

Summary

• add a package dry-run review artifact for the local nupkg inspection
• record package contents, nuspec metadata, README/license/XML docs findings, CI pack boundary, and NuGet ID suitability notes
• explicitly state that the review does not approve publishing or public release

Validation

• git diff --check
• dotnet format IntervalTree.Net.sln --verify-no-changes
• dotnet restore IntervalTree.Net.sln
• dotnet build IntervalTree.Net.sln --configuration Release --no-restore
• dotnet test IntervalTree.Net.sln --configuration Release --no-build
• dotnet pack src/IntervalTree.Net/IntervalTree.Net.csproj --configuration Release --no-build --output artifacts/package-dry-run
• inspected generated .nupkg contents and nuspec locally; generated artifacts were removed after inspection