feat(marketplace): add skill-creator plugin to marketplace registry

.claude-plugin/marketplace.json

@@ -427,6 +427,17 @@
       "category": "productivity",
       "homepage": "https://github.com/anthropics/claude-plugins-official/tree/main/plugins/claude-md-management"
     },
+    {
+      "name": "skill-creator",
+      "description": "Create new skills, improve existing skills, and measure skill performance. Use when users want to create a skill from scratch, update or optimize an existing skill, run evals to test a skill, or benchmark skill performance with variance analysis.",
+      "author": {
+        "name": "Anthropic",
+        "email": "support@anthropic.com"
+      },
+      "source": "./plugins/skill-creator",
+      "category": "development",
+      "homepage": "https://github.com/anthropics/claude-plugins-official/tree/main/plugins/skill-creator"
+    },
     {
       "name": "greptile",
       "description": "AI-powered codebase search and understanding. Query your repositories using natural language to find relevant code, understand dependencies, and get contextual answers about your codebase architecture.",