V10.0.1/fix versioning #2

[gimlichael]

This pull request introduces several improvements to the CI pipeline and build configuration to ensure the integrity and correctness of release packages. The main focus is on validating the release version and package before publishing, and on enforcing consistent version tagging. Below are the most important changes:

CI Pipeline Enhancements:

• Added a new release_version_guard job to .github/workflows/ci-pipeline.yml that validates the calculated release version after the build. This job ensures that a valid SemVer tag is present and prevents publishing if the version is a fallback (e.g., 0.0.0-alpha).
• Updated the pack job to depend on the new release_version_guard, ensuring that packaging only proceeds if the release version is validated.
• Added a validation step after packaging to check that exactly one .nupkg file is produced, and that its filename, package id, and version match the expected values. This step also inspects the .nuspec file inside the package for correctness, preventing accidental publication of invalid packages.
• Changed the NuGet publish step to push only the validated package file, rather than all .nupkg files in the directory.

Build Configuration Improvements:

• In Directory.Build.props, added logic to set the MinVerTagPrefix to v for source projects, enforcing that only tags prefixed with v are recognized for versioning. [1] [2]

These changes collectively improve the reliability of the release process by enforcing strict version and package validation before publication.