fix: 完善多云同步验证与实例统计

- 修复华为云签名、账单字段与区域映射缓存
- 按真实云实例更新账号服务器数并补充并发测试

backend/cloud/huawei_billing_test.go

@@ -0,0 +1,45 @@
+package cloud
+
+import (
+	"testing"
+)
+
+func TestDecodeHuaweiBillPageRecords(t *testing.T) {
+	body := []byte(`{
+		"currency":"CNY",
+		"total_count":1,
+		"records":[{
+			"service_type_name":"弹性云服务器",
+			"region_name":"华南-广州",
+			"consume_amount":"12.34"
+		}]
+	}`)
+	page, err := decodeHuaweiBillPage(body)
+	if err != nil {
+		t.Fatalf("解析华为云账单失败: %v", err)
+	}
+	if page.TotalCount != 1 || page.Currency != "CNY" || len(page.Records) != 1 {
+		t.Fatalf("账单分页字段错误: %+v", page)
+	}
+	record := page.Records[0]
+	if record.ServiceTypeName != "弹性云服务器" || record.RegionName != "华南-广州" {
+		t.Fatalf("账单维度字段错误: %+v", record)
+	}
+	if cost := huaweiBillRecordCost(record); cost != 12.34 {
+		t.Fatalf("实际消费金额错误: %v", cost)
+	}
+}
+
+func TestDecodeHuaweiBillPageFeeRecordsCompatibility(t *testing.T) {
+	body := []byte(`{"total_count":1,"fee_records":[{"official_amount":20,"discount_amount":3}]}`)
+	page, err := decodeHuaweiBillPage(body)
+	if err != nil {
+		t.Fatalf("解析旧版华为云账单失败: %v", err)
+	}
+	if len(page.FeeRecords) != 1 {
+		t.Fatalf("旧版 fee_records 未解析: %+v", page)
+	}
+	if cost := huaweiBillRecordCost(page.FeeRecords[0]); cost != 17 {
+		t.Fatalf("官网价减优惠金额错误: %v", cost)
+	}
+}