fix(storage): 补齐嵌套结果二进制转存

生产真实 Gemini 图片任务可能在标准 data 之外保留嵌套 Base64，导致最终持久化关口拒绝任务成功。\n\n在所有生成结果返回前统一执行递归转存，并对仍未被常规媒体转换识别的二进制回退到本地结果物化，确保 PostgreSQL 不接收原始二进制。\n\n验证：go test ./... -count=1；go vet ./...；使用生产 Gemini Flash Image 平台配置完成本地真实图片编辑请求，文件哈希一致且持久化结果无内联二进制。

apps/api/internal/runner/upload_test.go

@@ -236,6 +236,52 @@ func TestGeneratedAssetUploadPolicyFromName(t *testing.T) {
 	}
 }
 
+func TestFinalizeGeneratedAssetsUploadsNestedInlineBinaryUnderDefaultPolicy(t *testing.T) {
+	storageDir := t.TempDir()
+	service := &Service{cfg: config.Config{LocalGeneratedStorageDir: storageDir}}
+	payload := append([]byte{0x89, 'P', 'N', 'G', 0x0d, 0x0a, 0x1a, 0x0a}, bytes.Repeat([]byte{0}, 160)...)
+	encoded := base64.StdEncoding.EncodeToString(payload)
+	result := map[string]any{
+		"id": "image-edit",
+		"provider_result": map[string]any{
+			"binary_data_base64": encoded,
+			"mime_type":          "image/png",
+		},
+	}
+
+	finalized, err := service.finalizeGeneratedAssets(
+		context.Background(),
+		"task-nested-binary",
+		"images.edits",
+		result,
+		defaultGeneratedAssetUploadPolicy(),
+		nil,
+		true,
+		0,
+	)
+	if err != nil {
+		t.Fatalf("finalize generated assets: %v", err)
+	}
+	if TaskResultHasInlineBinary(finalized) {
+		t.Fatal("finalized result still contains inline binary")
+	}
+	nested := finalized["provider_result"].(map[string]any)
+	reference, ok := nested["binary_data_base64"].(map[string]any)
+	if !ok {
+		t.Fatalf("nested binary should be replaced by an asset reference: %+v", nested)
+	}
+	if urlValue := stringFromAny(reference["url"]); !strings.HasPrefix(urlValue, "/static/generated/gateway-result-task-nested-binary-01-") {
+		t.Fatalf("unexpected local static URL: %s", urlValue)
+	}
+	entries, err := os.ReadDir(storageDir)
+	if err != nil {
+		t.Fatalf("read generated storage: %v", err)
+	}
+	if len(entries) != 1 {
+		t.Fatalf("expected one localized result file, got %d", len(entries))
+	}
+}
+
 func TestResolvedGeneratedAssetContentTypePrefersDetectedMedia(t *testing.T) {
 	pngPayload := []byte{0x89, 'P', 'N', 'G', 0x0d, 0x0a, 0x1a, 0x0a, 0, 0, 0, 0}