Sync with TemplateDotNetTool template updates (commits #41, #45, #46, #47)

[Copilot]

Applies four recent upstream template changes to keep SpdxTool in sync with TemplateDotNetTool.

Description

csproj changes:

• LangVersion 12 → latest in main tool csproj (Packages should be checked for existence when adding references. #41)
• Add Polyfill 9.12.0 as a PrivateAssets="All" build-tool dependency (Packages should be checked for existence when adding references. #41)
• Reorganize main csproj ItemGroup blocks into labeled sections: Runtime Dependencies, Build Tool Dependencies, Code Analysis Dependencies (Copying packages should allow for control of files #47)
• Add <!-- Implicit Usings --> section with <Using Include="Polyfills" /> to both test csproj files (Clean up generation of SPDX package IDs. #46)

Agent guidance:

• Add MSTest antipattern Added new commands to tool #5 (Assert.StartsWith) to test-developer.md (Update dependencies to patch for CVE-2024-30105 #45)
• Add missing Tests and Requirements and Test Source Filters sections to test-developer.md
• Add Requirements Agent to Defer To section

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code quality improvement

Related Issues

Pre-Submission Checklist

Before submitting this pull request, ensure you have completed the following:

Build and Test

• Code builds successfully: dotnet build --configuration Release
• All unit tests pass: dotnet test --configuration Release
• Self-validation tests pass:
  dotnet run --project src/DemaConsulting.SpdxTool --configuration Release --framework net10.0
--no-build -- --validate
• Code produces zero warnings

Code Quality

• Code formatting is correct: dotnet format --verify-no-changes
• New code has appropriate XML documentation comments
• Static analyzer warnings have been addressed

Quality Checks

Please run the following checks before submitting:

• Spell checker passes: cspell "**/*.{md,cs}"
• Markdown linter passes: markdownlint "**/*.md"
• YAML linter passes: yamllint .

Testing

• Added unit tests for new functionality
• Updated existing tests if behavior changed
• All tests follow the AAA (Arrange, Act, Assert) pattern
• Test coverage is maintained or improved

Documentation

• Updated README.md (if applicable)
• Updated ARCHITECTURE.md (if applicable)
• Added code examples for new features (if applicable)
• Updated requirements.yaml (if applicable)

Additional Notes

Polyfill 9.12.0 cleared the GitHub advisory database check with no vulnerabilities found.

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