fix(ai): pass baseUrl to Google GenAI SDK via httpOptions

Previously, when using 'google-generative-ai' API with a custom baseUrl
in models.json, the baseUrl was ignored and requests always went to the
default Google endpoint.

Now the provider correctly passes model.baseUrl to the SDK's
httpOptions.baseUrl, enabling use of custom endpoints or API proxies.

Fixes #216

packages/ai/src/providers/google.ts

@@ -258,9 +258,18 @@ function createClient(model: Model<"google-generative-ai">, apiKey?: string): Go
 		}
 		apiKey = process.env.GEMINI_API_KEY;
 	}
+
+	const httpOptions: { baseUrl?: string; headers?: Record<string, string> } = {};
+	if (model.baseUrl) {
+		httpOptions.baseUrl = model.baseUrl;
+	}
+	if (model.headers) {
+		httpOptions.headers = model.headers;
+	}
+
 	return new GoogleGenAI({
 		apiKey,
-		httpOptions: model.headers ? { headers: model.headers } : undefined,
+		httpOptions: Object.keys(httpOptions).length > 0 ? httpOptions : undefined,
 	});
 }