add update script

Author: kentcdodds

package.json

@@ -33,6 +33,7 @@
     "postinstall": "cd ./epicshop && npm install",
     "start": "npx --prefix ./epicshop epicshop start",
     "dev": "npx --prefix ./epicshop epicshop start",
+    "update": "npx --prefix ./epicshop epicshop update",
     "dev:mcp": "node ./epicshop/run.js",
     "inspect": "npx @kentcdodds/tmp-modelcontextprotocol_inspector",
     "test": "npm run test --silent --prefix playground",