feat(search): surface compliance mappings in discovery

[XiaoSeS]

Summary

Second small PR for Issue #556 after #697. This PR surfaces the version-level x-astron-compliance snapshot in discovery/search results so users can find and recognize skills by compliance mapping.

What changed:

• Add complianceSnapshot to SkillSummaryResponse.
• Project the headline published version compliance snapshot into search results.
• Include compliance mappings in discovery cards and add search suggestion chips for MITRE/NIST/SOC2/GDPR keywords.
• Keep this scoped: no new compliance API, no review/audit diff, no Astron runtime trace integration.

Validation

Source checks:

• cd server && ./mvnw -pl skillhub-app -am -Dtest=SkillSearchAppServiceTest -Dsurefire.failIfNoSpecifiedTests=false test
• cd web && pnpm exec vitest run src/features/skill/skill-card.test.ts src/pages/search.test.tsx
• cd web && pnpm run typecheck
• make lint-web
• cd web && pnpm run build
• git diff --check

Runtime preview:

• Built exact-SHA local server image: skillhub-preview-compliance-projection-server:sha-00f55c2db3f2
• Built exact-SHA local web image: skillhub-preview-compliance-projection-web:sha-00f55c2db3f2
• Reused stable scanner image because scanner code is unchanged.
• Started release Compose project skillhub-compliance-projection-00f55c2d with dynamic loopback ports.
• Published a real skill package containing MITRE ATT&CK T1059 and NIST CSF PR.DS-01 compliance metadata.
• Verified /api/web/skills?q=MITRE%20T1059 and /api/web/skills?q=NIST%20PR.DS-01 both return the published skill with complianceSnapshot.
• Verified an unrelated query returns 0 results.
• Verified web runtime config and web proxy /api/web/skills path.

Private HTML report: /home/ylhu16/skillhub-local-reports/runs/issue-556-compliance-projection-20260807/report.html

Notes

GitHub official/HK validation is not required for this PR because it does not change Dockerfiles, Compose/Kubernetes, runtime config, registry publishing, or deployment behavior.

Signed-off-by: XiaoSeS 87064762+XiaoSeS@users.noreply.github.com