Update stagehand.mdx

add missing dependency

Author: kathayl

src/content/docs/browser-rendering/platform/stagehand.mdx

@@ -159,6 +159,7 @@ Ensure your `package.json` has the following dependencies:
 		"dependencies": {
 			"@browserbasehq/stagehand": "^2.5.0",
 			"@cloudflare/playwright": "^1.0.0",
+			"playwright-core",
 			"zod": "^3.25.76",
 			"zod-to-json-schema": "^3.24.6"
 			// ...