ensure shelf name is unique

internal/types/shelves.go

@@ -12,7 +12,7 @@ import (
 
 type ShelfLocation struct {
 	ID          uint64         `gorm:"primarykey" json:"id"`
-	Name        string         `json:"name"`
+	Name        string         `gorm:"index:unique" json:"name"`
 	RoomNumber  string         `json:"room_number,omitempty"`
 	Description string         `json:"description,omitempty"`
 	BuildingID  uint64         `json:"-"`