feat: add interactive HTML standards reports

[machado144]

Summary

• add --html-output and a yamlspec report command for self-contained interactive standards reports
• add yamlspec serve for local report viewing
• embed original specs and rendered manifest files in reports so failed assertions can be debugged from one artifact
• update the reusable workflow to upload yamlspec-results.html alongside JSON, EMD, and JUnit
• align the report UI with AxeForge dark navy/orange branding
• improve reviewer UX with failure focus cards, failures-only filtering, expand/collapse controls, shortened paths, assertion counts, collapsible evidence panes, and mixed pass/fail density handling
• bump module Go version to 1.25.10 so vulnerability scanning uses the patched standard library

Verification

• /home/youngestaxe/go/bin/go1.25.10 test ./...
• govulncheck ./...
• pre-push govulncheck: no vulnerabilities found
• generated passing sample: /tmp/yamlspec-report-passing.html
• generated failing sample: /tmp/yamlspec-report-failing.html
• generated mixed pass/fail sample: /tmp/yamlspec-report-mixed.html