docs(guide): rewrite CLAUDE.md with ZCLAW-first perspective

Major changes:
- Shift from "OpenFang desktop client" to "independent AI Agent desktop app"
- Add decision principle: "Is this useful for ZCLAW? Does it affect ZCLAW?"
- Simplify project structure and tech stack sections
- Replace OpenClaw vs OpenFang comparison with unified backend approach
- Consolidate troubleshooting from scattered sections into organized FAQ
- Update Hands system documentation with 8 capabilities and status
- Stream

desktop/src/components/SkillMarket/SkillCard.tsx

@@ -120,7 +120,7 @@ export function SkillCard({
             px-3 py-1.5 rounded-lg text-xs font-medium transition-all duration-200
             ${skill.installed
               ? 'bg-gray-100 dark:bg-gray-700 text-gray-600 dark:text-gray-400 hover:bg-gray-200 dark:hover:bg-gray-600'
-              : 'bg-blue-500 text-white hover:bg-blue-600'
+              : 'bg-gray-700 dark:bg-gray-600 text-white hover:bg-gray-800 dark:hover:bg-gray-500'
             }
           `}
         >