feat: support bundle-aware skill sync and dashboard versioning

[StoneHanaMori]

Summary

• add bundle-aware skill sync so SkillClaw can upload, pull, and version full skill directories instead of only SKILL.md
• preserve extra semi-structured skill assets such as references/, scripts/, assets/, history/, and other nested files through shared storage round trips
• make evolve-server and agent workspace detect and publish nested bundle changes during skill evolution
• update dashboard sync/version activation to compare bundle tree hashes and restore full shared skill bundles locally
• add regression coverage for single-file skills, multi-file bundles, extra-file round trips, and dashboard bundle activation