refactor: initialize shelf states in LibraryViewModel for improved it…

…em loading

- Added initShelfStates method to initialize shelfStates for all ShelfType cases, enhancing state management.
- Updated selectedCategory property to call initShelfStates and loadAllShelfItems when changed, ensuring consistent shelf item loading and state updates.

NeoDB/NeoDB/Views/Library/LibraryViewModel.swift

@@ -32,6 +32,7 @@ final class LibraryViewModel: ObservableObject {
     @Published var selectedCategory: ItemCategory.shelfAvailable = .allItems {
         didSet {
             if oldValue != selectedCategory {
+                initShelfStates()
                 loadAllShelfItems()
             }
         }
@@ -61,6 +62,12 @@ final class LibraryViewModel: ObservableObject {
     var currentShelfState: ShelfItemsState {
         shelfStates[selectedShelfType] ?? ShelfItemsState()
     }
+
+    func initShelfStates() {
+        for type in ShelfType.allCases {
+            shelfStates[type] = ShelfItemsState()
+        }
+    }
 
     // MARK: - Public Methods
     func loadShelfItems(type: ShelfType, refresh: Bool = false) async {