Refactor skill lifecycle projection and docs

[vsxd]

Summary

• unify skill lifecycle reads around a single backend projection for detail, my-skills, stars, search, and compat mapping
• normalize lifecycle semantics by making withdraw-review revert pending versions to draft and recomputing latest published pointer on yank
• migrate frontend pages and docs to the new lifecycle model and remove old compatibility fields/logic

Testing

• cd server && ./mvnw -pl skillhub-domain,skillhub-app -am test -Dtest=SkillQueryServiceTest,SkillSearchAppServiceTest,ReviewServiceTest,SkillGovernanceServiceTest,MySkillAppServiceTest,SkillLifecycleControllerTest,SkillControllerTest,MeControllerTest,ClawHubCompatControllerTest -Dsurefire.failIfNoSpecifiedTests=false
• cd web && pnpm install
• cd web && pnpm typecheck
• cd web && pnpm test