Align self-validation output format with TemplateDotNetTool style

[Copilot]

Pull Request

Description

Self-validation output was using a plain - SpdxTool_Xxx: Passed/Failed list format. This aligns it with the TemplateDotNetTool pattern from PR #51, replacing it with checkmark symbols and adding a summary block.

Before:

Tests:

- SpdxTool_AddPackage: Passed
- SpdxTool_Validate: Failed
...

Validation Passed

After:

✓ SpdxTool_AddPackage - Passed
✗ SpdxTool_Validate - Failed
...

Total Tests: 14
Passed: 13
Failed: 1

Changes

• 14 Validate*.cs files — Replace context.WriteLine($"- SpdxTool_Xxx: Passed/Failed") with ✓/✗ prefix format; failures now use context.WriteError so they surface as errors
• Validate.cs — Remove Tests: section header from output; add Total Tests / Passed / Failed summary block after all tests run (failed count uses WriteError)
• README.md / docs/guide/guide.md — Update example validation report to match new output format

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

The Validation Passed message is retained after the summary block as existing tests assert on it.

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