fix: Gemini 2.5 requests fail when frequency or presence penalties are configured (#18051)

## Background

Gemini 2.5 Flash, Flash-Lite, and Pro returned HTTP 400 INVALID_ARGUMENT
when frequencyPenalty or presencePenalty was configured through
@ai-sdk/google.

## Root Cause

GoogleLanguageModel forwarded penalty settings unconditionally. Fixture
and live API reproductions confirmed that Gemini 2.5 rejects those
request fields while equivalent requests without them succeed.

## Summary

Gemini 2.5 requests now omit unsupported penalty settings and return
unsupported warnings. Gemini 2.0 forwarding remains unchanged, and a
patch changeset was added.

## Testing

Added regression cases for both penalties across Gemini 2.5 Pro, Flash,
and Flash-Lite, plus coverage confirming Gemini 2.0 still receives both
settings.

## End-to-end Validation

- `pnpm -C packages/google build` followed by `pnpm -C
examples/ai-functions exec tsx -e <live validation>`: all six Gemini 2.5
requests omitted penalties, emitted the expected warnings, and returned
HTTP 200.

## Related Issues

Fixes #8943

Closes #17862

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Co-authored-by: ai-sdk-factory <308175966+ai-sdk-factory@users.noreply.github.com>
Co-authored-by: lgrammel <lars.grammel@gmail.com>
Co-authored-by: ndaidong <1809619+ndaidong@users.noreply.github.com>
Co-authored-by: Lars Grammel <205036+lgrammel@users.noreply.github.com>
Co-authored-by: Aayush Kapoor <83492835+aayush-kapoor@users.noreply.github.com>