feat: deduplicate ship name on transfer

internal/error/input.go

@@ -124,10 +124,6 @@ func NewShipsNotOnSamePlanetError(arg ...any) error {
 	return newGenericError(ErrShipsNotOnSamePlanet, arg...)
 }
 
-func NewGiveawayGroupShipsTypeNotEqualError(arg ...any) error {
-	return newGenericError(ErrGiveawayGroupShipsTypeNotEqual, arg...)
-}
-
 func NewTechUnknownError(arg ...any) error {
 	return newGenericError(ErrInputTechUnknown, arg...)
 }