fix: clear checkboxes on new search query (#66)

This PR addresses an issue where the "download selected" functionality
behaves unexpectedly. If a user makes a selection of books to download,
performs a new search without clearing the previous selection, and
selects new books, clicking "download selected" would still include the
books from the prior selection. This causes the "download selected"
button to fail, as the books from the previous selection are no longer
available.


A potential enhancement could allow users to select books across
multiple searches and download them collectively. This could be achieved
by creating a dedicated section in the UI to track and display the
currently selected books. This feature might go well with a broader UI
overhaul, as has been suggested in some issues - maybe after your CF
bypass rewrite?

Co-authored-by: CaliBrain <calibrain@l4n.xyz>

static/js/main.js

@@ -221,7 +221,11 @@ document.addEventListener('DOMContentLoaded', () => {
                 utils.fetchJson(`${API_ENDPOINTS.download}?id=${encodeURIComponent(bookId)}`)
             );
 
-            // Uncheck all selected checkboxes
+            this.clearAllCheckboxes();
+            modal.close();
+        },
+
+        clearAllCheckboxes() {
             selectedBooks.forEach((bookId) => {
                 const checkbox = document.getElementById(`book-${bookId}`);
                 if (checkbox) checkbox.checked = false;
@@ -232,13 +236,13 @@ document.addEventListener('DOMContentLoaded', () => {
 
             selectedBooks.clear();
             utils.updateDownloadSelectedButton();
-            modal.close();
         }
     };
 
     // Search Functions
     const search = {
         async performSearch(query) {
+            utils.clearAllCheckboxes();
             if (STATE.isSearching) return;
 
             try {