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/controller/cloud_sync_test.go

@@ -0,0 +1,52 @@
+package controller
+
+import (
+	"errors"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"ezops/cloud"
+)
+
+type countInstancesProvider struct {
+	counts      map[string]int
+	failures    map[string]bool
+	activeCalls atomic.Int32
+	maxCalls    atomic.Int32
+}
+
+func (p *countInstancesProvider) Name() string { return "fake" }
+
+func (p *countInstancesProvider) ListRegions() ([]cloud.CloudRegion, error) { return nil, nil }
+
+func (p *countInstancesProvider) ListInstances(regionID string) ([]cloud.CloudInstance, error) {
+	active := p.activeCalls.Add(1)
+	defer p.activeCalls.Add(-1)
+	for {
+		maximum := p.maxCalls.Load()
+		if active <= maximum || p.maxCalls.CompareAndSwap(maximum, active) {
+			break
+		}
+	}
+	time.Sleep(5 * time.Millisecond)
+	if p.failures[regionID] {
+		return nil, errors.New("区域请求失败")
+	}
+	return make([]cloud.CloudInstance, p.counts[regionID]), nil
+}
+
+func TestCountCloudInstances(t *testing.T) {
+	provider := &countInstancesProvider{
+		counts:   map[string]int{"a": 2, "b": 3, "c": 4, "d": 5, "e": 6},
+		failures: map[string]bool{"c": true},
+	}
+	regions := []cloud.CloudRegion{{RegionID: "a"}, {RegionID: "b"}, {RegionID: "c"}, {RegionID: "d"}, {RegionID: "e"}}
+	total, succeeded := countCloudInstances(provider, regions)
+	if total != 16 || succeeded != 4 {
+		t.Fatalf("实例统计错误: total=%d succeeded=%d", total, succeeded)
+	}
+	if maximum := provider.maxCalls.Load(); maximum > 4 {
+		t.Fatalf("并发数超过限制: %d", maximum)
+	}
+}