feat(compliance): add compliance version mapping and audit snapshots

[dongmucat]

Summary

• add compliance metadata parsing, validation, search filtering, and version detail mappings across SkillHub backend and frontend
• record version-scoped compliance audit snapshots for lifecycle and publish paths, including portal, compat, CLI, and built-in auto-publish flows
• add targeted backend and frontend regression coverage for compliance mappings and latest-published audit snapshots

Test Plan

• cd server && ./mvnw -pl skillhub-domain -Dtest=SkillComplianceMetadataServiceTest,SkillPackageValidatorTest,SkillGovernanceServiceTest test
• cd server && ./mvnw -pl skillhub-search -Dtest=PostgresFullTextQueryServiceTest test
• cd server && ./mvnw -pl skillhub-app -am -Dtest=SkillSearchControllerTest,SkillSearchAppServiceTest,SkillControllerTest,SkillLifecycleAppServiceTest,ReviewPortalAppServiceTest,SkillPublishControllerTest,ClawHubCompatAppServiceTest,CliSkillAppServiceTest,CliSkillControllerTest -Dsurefire.failIfNoSpecifiedTests=false test
• cd web && pnpm exec vitest run src/shared/hooks/skill-query-helpers.test.ts src/pages/search.test.tsx
• cd web && pnpm run typecheck
• cd web && pnpm exec eslint src/pages/search.tsx src/pages/search.test.tsx src/shared/hooks/skill-query-helpers.ts src/shared/hooks/skill-query-helpers.test.ts src/pages/skill-detail.tsx src/pages/skill-detail.test.tsx src/app/router.tsx src/api/types.ts
• cd server && ./mvnw -pl skillhub-app -am -Dtest=BuiltinSkillInitializerTest,SkillPublishControllerTest,ClawHubCompatAppServiceTest,CliSkillAppServiceTest,CliSkillControllerTest -Dsurefire.failIfNoSpecifiedTests=false test

Human Gates

• human approval and explicit authorization are still required to merge this PR into main; no agent merge will be performed
• decide whether the manually synced web/src/api/generated/schema.d.ts is sufficient for this merge, or whether to require a local make generate-api run against an available :8080 OpenAPI service first
• decide whether to waive local execution of web/src/pages/skill-detail.test.tsx until the existing vitest/jsdom/html-encoding-sniffer ERR_REQUIRE_ESM environment issue is resolved

Closes #556