fix(gemini): 初始化图像生成配置对象

apps/api/internal/clients/clients_test.go

@@ -1306,6 +1306,25 @@ func TestGeminiClientImageGenerateBuildsNativeImageBody(t *testing.T) {
 	}
 }
 
+func TestGeminiGenerationConfigInitializesMissingImageConfig(t *testing.T) {
+	config := geminiGenerationConfig(map[string]any{
+		"aspect_ratio": "16:9",
+		"resolution":   "4K",
+	}, true)
+
+	imageConfig, ok := config["imageConfig"].(map[string]any)
+	if !ok {
+		t.Fatalf("imageConfig should be initialized, got %+v", config)
+	}
+	if imageConfig["aspectRatio"] != "16:9" || imageConfig["imageSize"] != "4K" {
+		t.Fatalf("unexpected imageConfig: %+v", imageConfig)
+	}
+	modalities, ok := config["responseModalities"].([]any)
+	if !ok || len(modalities) != 1 || modalities[0] != "IMAGE" {
+		t.Fatalf("image response modality should be initialized, got %+v", config)
+	}
+}
+
 func TestGeminiClientImageEditPreservesNativeContentsAndFileData(t *testing.T) {
 	var captured map[string]any
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {