Remove unused components and models for improved maintainability

- Deleted redundant components (`AddActionButton`, `AlertBox`, `AlertStack`, `BackButton`, `CancelButton`, and `CollapsableArea`) and related files.
- Removed unused models (`Book`, `BookSerie`, `BookTables`, `Character`, and `Chapter`) to reduce codebase clutter.
- Updated project structure and references to reflect these removals.

lib/utils/book.ts

@@ -0,0 +1,28 @@
+import {SelectBoxProps} from "@/components/form/SelectBox";
+import {SyncedBook} from "@/lib/types/synced-book";
+
+export function booksToSelectBox(books: SyncedBook[]): SelectBoxProps[] {
+    return books.map((book: SyncedBook): SelectBoxProps => {
+        return {
+            label: book.title,
+            value: book.id,
+        };
+    });
+}
+
+export function getBookTypeLabel(value: string): string {
+    switch (value) {
+        case 'short':
+            return 'bookTypes.short';
+        case 'novelette':
+            return 'bookTypes.novelette';
+        case 'long':
+            return 'bookTypes.novella';
+        case 'chapbook':
+            return 'bookTypes.chapbook';
+        case 'novel':
+            return 'bookTypes.novel';
+        default:
+            return 'bookTypes.novel';
+    }
+}