feat: add independent load_factor field for scheduling load calculation

- Separate load factor from concurrency: concurrency controls actual
  slot acquisition, load_factor controls load rate calculation
- Add EffectiveLoadFactor() method: LoadFactor > Concurrency > 1
- Add load_factor field to Create/Edit/BulkEdit account forms
- Fix RPM default value: auto-fill 15 when RPM enabled but not set
- Fix stale test compilation errors in server and handler packages

backend/ent/account/account.go

@@ -37,6 +37,8 @@ const (
 	FieldProxyID = "proxy_id"
 	// FieldConcurrency holds the string denoting the concurrency field in the database.
 	FieldConcurrency = "concurrency"
+	// FieldLoadFactor holds the string denoting the load_factor field in the database.
+	FieldLoadFactor = "load_factor"
 	// 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.
@@ -121,6 +123,7 @@ var Columns = []string{
 	FieldExtra,
 	FieldProxyID,
 	FieldConcurrency,
+	FieldLoadFactor,
 	FieldPriority,
 	FieldRateMultiplier,
 	FieldStatus,
@@ -250,6 +253,11 @@ func ByConcurrency(opts ...sql.OrderTermOption) OrderOption {
 	return sql.OrderByField(FieldConcurrency, opts...).ToFunc()
 }
 
+// ByLoadFactor orders the results by the load_factor field.
+func ByLoadFactor(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldLoadFactor, opts...).ToFunc()
+}
+
 // ByPriority orders the results by the priority field.
 func ByPriority(opts ...sql.OrderTermOption) OrderOption {
 	return sql.OrderByField(FieldPriority, opts...).ToFunc()