Sync third-party and MCP marketplace plugins

Constraint: Public skills are published only by explicit administrator action unless they are tracked third-party market sources.
Confidence: high
Scope-risk: narrow
Directive: Keep private/internal skills out of the public marketplace and preserve normal incremental market Git history.
Tested: Marketplace validation passed.

.agents/plugins/marketplace.json

@@ -268,18 +268,6 @@
       },
       "category": "开发工具"
     },
-    {
-      "name": "shadcn",
-      "source": {
-        "source": "local",
-        "path": "./plugins/codex/plugins/shadcn"
-      },
-      "policy": {
-        "installation": "AVAILABLE",
-        "authentication": "ON_INSTALL"
-      },
-      "category": "开发工具"
-    },
     {
       "name": "ui-ux-pro-max",
       "source": {
@@ -292,6 +280,18 @@
       },
       "category": "设计"
     },
+    {
+      "name": "shadcn",
+      "source": {
+        "source": "local",
+        "path": "./plugins/codex/plugins/shadcn"
+      },
+      "policy": {
+        "installation": "AVAILABLE",
+        "authentication": "ON_INSTALL"
+      },
+      "category": "开发工具"
+    },
     {
       "name": "ppt-master",
       "source": {