fix: remove broken self-reference dependency in stagehand package

Author: Kylejeong2

packages/stagehand/package.json

@@ -22,7 +22,6 @@
     "@browserbasehq/sdk": "^2.0.0",
     "@browserbasehq/stagehand": "^2.0.0",
     "@modelcontextprotocol/sdk": "^1.0.3",
-    "@modelcontextprotocol/server-stagehand": "file:",
     "@playwright/test": "^1.49.0",
     "dotenv": "^16.5.0"
   },