Rework storage structs, link preview

CHDataManagement/Model/Item/Item.swift

@@ -39,12 +39,20 @@ class Item: ObservableObject, Identifiable {
     var itemType: ItemType {
         fatalError()
     }
+
+    var itemReference: ItemReference {
+        fatalError()
+    }
+
+    var itemId: ItemId {
+        .init(type: itemType, id: id)
+    }
 }
 
 extension Item: Equatable {
 
     static func == (lhs: Item, rhs: Item) -> Bool {
-        lhs.id == rhs.id
+        lhs.id == rhs.id && lhs.itemType == rhs.itemType
     }
 }
 
@@ -52,12 +60,13 @@ extension Item: Hashable {
 
     func hash(into hasher: inout Hasher) {
         hasher.combine(id)
+        hasher.combine(itemType)
     }
 }
 
 extension Item: Comparable {
 
     static func < (lhs: Item, rhs: Item) -> Bool {
-        lhs.id < rhs.id
+        lhs.id < rhs.id && lhs.itemType < rhs.itemType
     }
 }