Add growthbook plugin (#4310)

.claude-plugin/marketplace.json

@@ -1562,6 +1562,20 @@
       "source": "./external_plugins/greptile",
       "homepage": "https://github.com/anthropics/claude-plugins-public/tree/main/external_plugins/greptile"
     },
+    {
+      "name": "growthbook",
+      "description": "A suite of agent skills for the full GrowthBook feature flag and experimentation lifecycle.",
+      "author": {
+        "name": "GrowthBook"
+      },
+      "category": "testing",
+      "source": {
+        "source": "url",
+        "url": "https://github.com/growthbook/skills.git",
+        "sha": "2ba1f3608d15394b2881125fc4babdc761454cb5"
+      },
+      "homepage": "https://growthbook.io"
+    },
     {
       "name": "honeycomb",
       "description": "Skills, agents, and workflows for Honeycomb observability — query patterns, production investigations, SLOs, OpenTelemetry instrumentation, and Beeline migration. Designed to complement the Honeycomb MCP server.",