fix: remove all external community references, use U-Claw branding

- Replace all openclaw-cn commands with openclaw (official)
- Remove OpenClaw-CN community fork links (jiulingyun)
- Remove clawd.org.cn, skillhub.tencent.com references
- Remove clawdbot-ai/awesome-openclaw-skills-zh links
- Update guide.html, llms.txt, skills.html, SkillHub.html, tutorial
- All links now point to U-Claw (u-claw.org) or OpenClaw official

website/skills.html

@@ -113,7 +113,7 @@ footer a{color:var(--accent)}
 </div>
 
 <footer>
-    <p>🦞 U-Claw 技能市场 · 数据来源 <a href="https://clawd.org.cn/market/" target="_blank">clawd.org.cn</a> · <a href="https://github.com/clawdbot-ai/awesome-openclaw-skills-zh" target="_blank">awesome-openclaw-skills-zh</a></p>
+    <p>🦞 U-Claw 技能市场 · 数据来源 <a href="https://u-claw.org" target="_blank">u-claw.org</a> · <a href="https://github.com/openclaw/clawhub" target="_blank">OpenClaw ClawHub</a></p>
     <p style="margin-top:8px"><a href="index.html">首页</a> · <a href="guide.html">使用指南</a> · <a href="https://github.com/dongsheng123132/u-claw">GitHub</a></p>
 </footer>