Add circleback plugin to marketplace

.claude-plugin/marketplace.json

@@ -566,16 +566,6 @@
         "url": "https://github.com/circlebackai/claude-code-plugin.git"
       },
       "homepage": "https://github.com/circlebackai/claude-code-plugin.git"
-    },
-    {
-      "name": "superpowers",
-      "description": "Superpowers teaches Claude brainstorming, subagent driven development with built in code review, systematic debugging, and red/green TDD. Additionally, it teaches Claude how to author and test new skills.",
-      "category": "development",
-      "source": {
-        "source": "url",
-        "url": "https://github.com/obra/superpowers.git"
-      },
-      "homepage": "https://github.com/obra/superpowers.git"
     }
   ]
 }