Gemini: INVALID_ARGUMENT when using built-in tools (GoogleSearch, etc.) with function calling

**Describe the bug**

When using built-in tools (e.g. `GoogleSearch`, `URLContext`) alongside custom function calling tools, the Gemini API returns:

```
Error 400, Message: Please enable tool_config.include_server_side_tool_invocations to use Built-in tools with Function calling., Status: INVALID_ARGUMENT
```

The `GenerateContentConfig.ToolConfig` needs `IncludeServerSideToolInvocations` set to `true` when both built-in tools and function declarations are present.

**To Reproduce**

1. Create a ChatModel with `EnableGoogleSearch` configured
2. Pass function calling tools via `schema.ToolInfo`
3. Call `Generate` or `Stream`
4. API returns `INVALID_ARGUMENT`

**Expected behavior**

The adapter should automatically set `ToolConfig.IncludeServerSideToolInvocations = true` when any built-in tool (GoogleSearch, URLContext, CodeExecution, ComputerUse, FileSearch, GoogleSearchRetrieval, GoogleMaps) is enabled alongside function declarations.

**Version:**

gemini@v0.1.29

**Environment:**

google.golang.org/genai v1.51.0+ (field added in this version)

**Additional context**

The `IncludeServerSideToolInvocations` field was added to `genai.ToolConfig` in `google.golang.org/genai` v1.51.0. The current `go.mod` pins `v1.36.0` which predates this field, so the fix also requires bumping the genai dependency.

Start in the Gemini adapter's handling of built-in tools and function declarations, then inspect go.mod for the google.golang.org/genai dependency. Reproduce the Generate and Stream cases with a built-in tool plus schema.ToolInfo, update the dependency as needed, and verify that both requests no longer return INVALID_ARGUMENT.

Written by the indexing model from the issue text.