feat: add 10 China-optimized skills, auto-install via setup.sh

Skills (40KB total, in portable/skills-cn/):
- deepseek-helper: DeepSeek API usage and model selection
- china-weather: Chinese city weather via wttr.in
- xiaohongshu-writer: 小红书爆款笔记写作
- wechat-article: 微信公众号文章写作
- douyin-script: 抖音/快手短视频脚本
- bilibili-helper: B站内容优化
- china-search: 百度/搜狗/Bing国内搜索
- zhihu-writer: 知乎回答写作
- weibo-poster: 微博内容创作
- china-translate: 中英互译+本地化

setup.sh auto-copies skills-cn/ into OpenClaw skills directory.
No external dependency on ClawHub for these skills.

portable/setup.sh

@@ -111,6 +111,23 @@ else
     echo -e "  ${GREEN}✓${NC} QQ 插件安装完成"
 fi
 
+# ---- 4. Install China-optimized skills ----
+SKILLS_CN="$SCRIPT_DIR/skills-cn"
+SKILLS_TARGET="$CORE_DIR/node_modules/openclaw/skills"
+
+if [ -d "$SKILLS_CN" ] && [ -d "$SKILLS_TARGET" ]; then
+    echo -e "  ${CYAN}↓${NC} 安装中国优化技能 (skills-cn)..."
+    SKILL_COUNT=0
+    for skill_dir in "$SKILLS_CN"/*/; do
+        skill_name=$(basename "$skill_dir")
+        if [ ! -d "$SKILLS_TARGET/$skill_name" ]; then
+            cp -R "$skill_dir" "$SKILLS_TARGET/$skill_name"
+            SKILL_COUNT=$((SKILL_COUNT + 1))
+        fi
+    done
+    echo -e "  ${GREEN}✓${NC} 中国技能安装完成 (+$SKILL_COUNT 个)"
+fi
+
 # ---- Done ----
 echo ""
 echo -e "${GREEN}════════════════════════════════════════${NC}"