Prepare clean v2.1.1 JOSS release

[HadenSmith]

Summary

• Inline the release workflow so the VSTest connection timeout can be increased for release builds.
• Refresh package, citation, CodeMeta, and README metadata for the v2.1.1 JOSS release.
• Update snapshot package base version to the next development patch line.

Details

The previous release job timed out while vstest.console was connecting to the testhost process, even though the test runs eventually completed successfully. The reusable release workflow does not expose a timeout input, so this PR mirrors that workflow locally and sets VSTEST_CONNECTION_TIMEOUT=600 for the release test step.

This also cleans up stale 2.0.0 metadata and avoids hard-coding a Zenodo DOI before the v2.1.1 archive exists; the README uses Zenodo's latest-DOI repository badge instead.

Validation

• dotnet build Numerics/Numerics.csproj -c Release /p:Version=2.1.1
• dotnet test -c Release with VSTEST_CONNECTION_TIMEOUT=600
• dotnet pack Numerics/Numerics.csproj -c Release /p:Version=2.1.1 --no-build -o ./packages