chore(mcp): update package to be private (#6606)

Author: joshblack

package-lock.json

@@ -1,7 +1,8 @@
 {
   "name": "@primer/mcp",
+  "private": true,
   "description": "An MCP server that connects AI tools to the Primer Design System",
-  "version": "0.0.2",
+  "version": "0.0.3",
   "type": "module",
   "bin": {
     "mcp": "./bin/mcp.js"