Implement Google Books API integration for book updates and enhance library management features

- Added a new endpoint in `index.js` to update book data using the Google Books API, allowing for real-time updates based on ISBN.
- Introduced a `rebuild_book_entries` function in `libraryManager.py` to facilitate user-driven updates of book entries from the Google Books API.
- Enhanced error handling and user prompts for better interaction during book updates.
- Updated `public/index.html` and `public/script.js` to improve the user interface and support new functionalities.
- Modified styles in `public/styles.css` to enhance the layout and usability of the checkout button and location prompt.

public/styles.css

@@ -197,4 +197,49 @@ body.dark-mode #book-table-body tr:hover {
     background-color: #444;
 }
 
+/* Center the checkout button and make it fill the cell */
+#book-table td button {
+    width: 100%;
+    height: 100%;
+    padding: 0;
+    margin: 0;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    box-sizing: border-box; /* Ensure padding and border are included in the element's total width and height */
+}
+
 /* Add more styles as needed for other elements */
+
+#location-prompt {
+    position: fixed;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%);
+    background-color: #fff;
+    color: #000;
+    padding: 20px;
+    border: 2px solid #000;
+    z-index: 1000;
+}
+
+#location-prompt label {
+    display: block;
+    margin-bottom: 5px;
+}
+
+#location-prompt input {
+    width: 100%;
+    padding: 8px;
+    margin-bottom: 10px;
+}
+
+#location-prompt select {
+    width: 100%;
+    padding: 8px;
+    margin-bottom: 10px;
+}
+
+#location-prompt button {
+    padding: 8px 16px;
+}