feat(计费): 支持账号计费倍率快照与统计展示

- 新增 accounts.rate_multiplier（默认 1.0，允许 0）
- 使用 usage_logs.account_rate_multiplier 记录倍率快照，避免历史回算
- 统计/导出/管理端展示账号口径费用（total_cost * account_rate_multiplier）

backend/ent/account/account.go

@@ -39,6 +39,8 @@ const (
 	FieldConcurrency = "concurrency"
 	// FieldPriority holds the string denoting the priority field in the database.
 	FieldPriority = "priority"
+	// FieldRateMultiplier holds the string denoting the rate_multiplier field in the database.
+	FieldRateMultiplier = "rate_multiplier"
 	// FieldStatus holds the string denoting the status field in the database.
 	FieldStatus = "status"
 	// FieldErrorMessage holds the string denoting the error_message field in the database.
@@ -116,6 +118,7 @@ var Columns = []string{
 	FieldProxyID,
 	FieldConcurrency,
 	FieldPriority,
+	FieldRateMultiplier,
 	FieldStatus,
 	FieldErrorMessage,
 	FieldLastUsedAt,
@@ -174,6 +177,8 @@ var (
 	DefaultConcurrency int
 	// DefaultPriority holds the default value on creation for the "priority" field.
 	DefaultPriority int
+	// DefaultRateMultiplier holds the default value on creation for the "rate_multiplier" field.
+	DefaultRateMultiplier float64
 	// DefaultStatus holds the default value on creation for the "status" field.
 	DefaultStatus string
 	// StatusValidator is a validator for the "status" field. It is called by the builders before save.
@@ -244,6 +249,11 @@ func ByPriority(opts ...sql.OrderTermOption) OrderOption {
 	return sql.OrderByField(FieldPriority, opts...).ToFunc()
 }
 
+// ByRateMultiplier orders the results by the rate_multiplier field.
+func ByRateMultiplier(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldRateMultiplier, opts...).ToFunc()
+}
+
 // ByStatus orders the results by the status field.
 func ByStatus(opts ...sql.OrderTermOption) OrderOption {
 	return sql.OrderByField(FieldStatus, opts...).ToFunc()

backend/ent/account/where.go

@@ -105,6 +105,11 @@ func Priority(v int) predicate.Account {
 	return predicate.Account(sql.FieldEQ(FieldPriority, v))
 }
 
+// RateMultiplier applies equality check predicate on the "rate_multiplier" field. It's identical to RateMultiplierEQ.
+func RateMultiplier(v float64) predicate.Account {
+	return predicate.Account(sql.FieldEQ(FieldRateMultiplier, v))
+}
+
 // Status applies equality check predicate on the "status" field. It's identical to StatusEQ.
 func Status(v string) predicate.Account {
 	return predicate.Account(sql.FieldEQ(FieldStatus, v))
@@ -675,6 +680,46 @@ func PriorityLTE(v int) predicate.Account {
 	return predicate.Account(sql.FieldLTE(FieldPriority, v))
 }
 
+// RateMultiplierEQ applies the EQ predicate on the "rate_multiplier" field.
+func RateMultiplierEQ(v float64) predicate.Account {
+	return predicate.Account(sql.FieldEQ(FieldRateMultiplier, v))
+}
+
+// RateMultiplierNEQ applies the NEQ predicate on the "rate_multiplier" field.
+func RateMultiplierNEQ(v float64) predicate.Account {
+	return predicate.Account(sql.FieldNEQ(FieldRateMultiplier, v))
+}
+
+// RateMultiplierIn applies the In predicate on the "rate_multiplier" field.
+func RateMultiplierIn(vs ...float64) predicate.Account {
+	return predicate.Account(sql.FieldIn(FieldRateMultiplier, vs...))
+}
+
+// RateMultiplierNotIn applies the NotIn predicate on the "rate_multiplier" field.
+func RateMultiplierNotIn(vs ...float64) predicate.Account {
+	return predicate.Account(sql.FieldNotIn(FieldRateMultiplier, vs...))
+}
+
+// RateMultiplierGT applies the GT predicate on the "rate_multiplier" field.
+func RateMultiplierGT(v float64) predicate.Account {
+	return predicate.Account(sql.FieldGT(FieldRateMultiplier, v))
+}
+
+// RateMultiplierGTE applies the GTE predicate on the "rate_multiplier" field.
+func RateMultiplierGTE(v float64) predicate.Account {
+	return predicate.Account(sql.FieldGTE(FieldRateMultiplier, v))
+}
+
+// RateMultiplierLT applies the LT predicate on the "rate_multiplier" field.
+func RateMultiplierLT(v float64) predicate.Account {
+	return predicate.Account(sql.FieldLT(FieldRateMultiplier, v))
+}
+
+// RateMultiplierLTE applies the LTE predicate on the "rate_multiplier" field.
+func RateMultiplierLTE(v float64) predicate.Account {
+	return predicate.Account(sql.FieldLTE(FieldRateMultiplier, v))
+}
+
 // StatusEQ applies the EQ predicate on the "status" field.
 func StatusEQ(v string) predicate.Account {
 	return predicate.Account(sql.FieldEQ(FieldStatus, v))