Add a release workflow that publishes to NuGet with Trusted Publishing

[archofthings]

Adds .github/workflows/release.yml, which publishes Cimon.Net to nuget.org and creates a GitHub release. NuGet currently has only 1.0.0, so this is what will publish 2.0.0.

How it runs

• On a pushed v* tag, for example v2.1.0.
• By hand from the Actions tab (Run workflow, then enter a tag). This releases a tag that already exists, such as the current v2.0.0, which points at main, without deleting and re-creating it.

Steps

1. Checks out the tag and checks that it matches <Version> in CimonPlc.csproj.
2. Runs the tests (sets up the .NET 8 and 10 SDKs, like CI).
3. Packs Cimon.Net.<version>.nupkg and the .snupkg symbols package.
4. Takes the release notes from that version's section in CHANGELOG.md, falling back to a changelog link.
5. Logs in with NuGet/login@v1 (Trusted Publishing): a GitHub OIDC token is exchanged for an API key that expires after about an hour, so no NuGet key is stored in the repository.
6. Pushes the package and symbols to nuget.org with --skip-duplicate, so re-runs are safe.
7. Creates the GitHub release "Cimon.Net " with the changelog notes and both package files.

Setup needed before running it

• A Trusted Publishing policy on nuget.org: owner archofthings, repository Cimon.Net, workflow release.yml, package Cimon.Net, scope "push only new package versions".
• A repository secret NUGET_USER with the nuget.org profile name.

Testing

• dotnet test -c Release: 149 tests pass.
• dotnet pack produces Cimon.Net.2.0.0.nupkg and Cimon.Net.2.0.0.snupkg.
• The changelog extraction outputs exactly the ## 2.0.0 section.
• The workflow YAML parses. The workflow itself only runs on a tag or by hand, so its first real run will be the 2.0.0 release. The same Trusted Publishing setup published Rony.Net 1.0.0 successfully.

After merging

Go to Actions → Release → Run workflow, keep the branch as main, and enter the tag v2.0.0.

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

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