feat: add independent load_factor field for scheduling load calculation

backend/internal/handler/dto/mappers.go

@@ -183,6 +183,7 @@ func AccountFromServiceShallow(a *service.Account) *Account {
 		Extra:                   a.Extra,
 		ProxyID:                 a.ProxyID,
 		Concurrency:             a.Concurrency,
+		LoadFactor:              a.LoadFactor,
 		Priority:                a.Priority,
 		RateMultiplier:          a.BillingRateMultiplier(),
 		Status:                  a.Status,

backend/internal/handler/dto/types.go

@@ -131,6 +131,7 @@ type Account struct {
 	Extra              map[string]any `json:"extra"`
 	ProxyID            *int64         `json:"proxy_id"`
 	Concurrency        int            `json:"concurrency"`
+	LoadFactor         *int           `json:"load_factor,omitempty"`
 	Priority           int            `json:"priority"`
 	RateMultiplier     float64        `json:"rate_multiplier"`
 	Status             string         `json:"status"`