Rename and refocus the StarryKit Skill

[Mine77]

Summary

• rename the canonical Skill from starrykit-authoring to starrykit
• rebuild the main Skill around reference-driven design, document planning, page direction, and visual verification
• move exact Hosted MCP lifecycle, export, and recovery rules into a focused reference
• update manifests, installation commands, bilingual host docs, and validation coverage

Verification

• python3 /home/haichao/.codex/skills/.system/skill-creator/scripts/quick_validate.py skills/starrykit
• npm test
• git diff --check