refactor: 通用技能按类别拆分为独立目录

skills/ → skills-dev(9), skills-req(10), skills-ops(4),
skills-integration(8), skills-biz(4), skills-workflow(7)

generate-marketplace.py 改为自动扫描所有 skills-* 目录。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

skills-integration/feishu-plugin/users.json

@@ -0,0 +1,10 @@
+{
+  "吴薇儿": {
+    "email": "wuweier@zhiyuncai.com",
+    "open_id": "ou_1d5cdfee78cbe6f8acc0751fff00ed09"
+  },
+  "宋佳香": {
+    "email": "songjiaxiang@zhiyuncai.com",
+    "open_id": "e6e72eb8"
+  }
+}