fix(browser-automation): upgrade stagehand to support sonnet 4.6 for CUA

Stagehand v3.0.x does not include claude-sonnet-4-6 in its CUA model
allowlist, causing browser automations to fail. Upgrading to v3.2.1
adds support for the model.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: tofikwest

apps/api/package.json

@@ -60,7 +60,7 @@
         "@aws-sdk/client-transfer": "^3.948.0",
         "@aws-sdk/s3-request-presigner": "3.1013.0",
         "@browserbasehq/sdk": "2.6.0",
-        "@browserbasehq/stagehand": "^3.0.5",
+        "@browserbasehq/stagehand": "^3.2.1",
         "@mendable/firecrawl-js": "^4.9.3",
         "@nestjs/common": "^11.0.1",
         "@nestjs/config": "^4.0.2",