fix(google): add gemini 3 support for file search tool

[shubham-021]

Background

The gemini api file search tool currently doesn't support gemini-3-pro-preview , even though Google's official documentation lists it as a supported model for File Search.

Summary

• updated supportsFileSearch check in google-prepare-tools.ts to include gemini 3 models
• updated the error message to reflect the new supported models
• added a test case for file search with gemini-3 models

Manual Verification

• Added tests

Checklist

• Tests have been added / updated (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)
• A patch changeset for relevant packages has been added (for bug fixes / features - run pnpm changeset in the project root)
• I have reviewed this pull request (self-review)

Fixes : #11161

[georgezhai123]

@R-Taneja , @lgrammel , can the team merge this fix please? Thanks!

[lgrammel]

cc @gr2m

[georgezhai123]

@gr2m
Can you merge this fix please? Thanks!

[georgezhai123]

@lgrammel This fix still hasn't got merged. This is critical for our system to have Gemini 3 supported for file search tool. Can we escalate and merge this fix ? Thank you!

[peka2]

I’m seeing the same error, so I’d appreciate it if you could merge this fix.