fix(google): auto-inject skip_thought_signature_validator on Gemini 3 replays

[gr2m]

Background

Gemini 3 rejects replayed assistant functionCall parts without thoughtSignature with HTTP 400. This happens when app/client code persists or rebuilds messages and drops providerOptions.

Summary

• For Gemini 3 only (/^gemini-3[.-]/), inject Google's documented skip_thought_signature_validator sentinel when a replayed tool call has no signature.
• Warn once per request with affected tool names.
• Adapted to main V4 Google provider files and existing google / googleVertex / vertex namespace lookup.

Manual Verification

Live replay against google('gemini-3-flash-preview'): missing-signature replay changed from HTTP 400 to HTTP 200 with warning.

Checklist

• All commits are signed (PRs with unsigned commits cannot be merged)
• 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)

Related Issues

Closes #15550.
Refs #10344, #11413, #14196, #15548, #13060.

[github-actions]

🚀 Published in:

Package	Version
ai	7.0.0-canary.155 github npm
@ai-sdk/amazon-bedrock	5.0.0-canary.71 github npm
@ai-sdk/angular	3.0.0-canary.155 github npm
@ai-sdk/google	4.0.0-canary.74 github npm
@ai-sdk/google-vertex	5.0.0-canary.96 github npm
@ai-sdk/langchain	3.0.0-canary.155 github npm
@ai-sdk/llamaindex	3.0.0-canary.155 github npm
@ai-sdk/otel	1.0.0-canary.101 github npm
@ai-sdk/react	4.0.0-canary.157 github npm
@ai-sdk/rsc	3.0.0-canary.156 github npm
@ai-sdk/svelte	5.0.0-canary.155 github npm
@ai-sdk/vue	4.0.0-canary.155 github npm
@ai-sdk/workflow	1.0.0-canary.72 github npm