refactor: 调整项目结构为单向依赖

backend/internal/service/usage_log.go

@@ -0,0 +1,53 @@
+package service
+
+import "time"
+
+const (
+	BillingTypeBalance      int8 = 0 // 钱包余额
+	BillingTypeSubscription int8 = 1 // 订阅套餐
+)
+
+type UsageLog struct {
+	ID        int64
+	UserID    int64
+	ApiKeyID  int64
+	AccountID int64
+	RequestID string
+	Model     string
+
+	GroupID        *int64
+	SubscriptionID *int64
+
+	InputTokens         int
+	OutputTokens        int
+	CacheCreationTokens int
+	CacheReadTokens     int
+
+	CacheCreation5mTokens int
+	CacheCreation1hTokens int
+
+	InputCost         float64
+	OutputCost        float64
+	CacheCreationCost float64
+	CacheReadCost     float64
+	TotalCost         float64
+	ActualCost        float64
+	RateMultiplier    float64
+
+	BillingType  int8
+	Stream       bool
+	DurationMs   *int
+	FirstTokenMs *int
+
+	CreatedAt time.Time
+
+	User         *User
+	ApiKey       *ApiKey
+	Account      *Account
+	Group        *Group
+	Subscription *UserSubscription
+}
+
+func (u *UsageLog) TotalTokens() int {
+	return u.InputTokens + u.OutputTokens + u.CacheCreationTokens + u.CacheReadTokens
+}