Show available space of storages.

frontend/src/pages/manage_storage_page.tsx

@@ -79,6 +79,7 @@ export default function StorageView() {
         <tr>
           <td>{t("Name")}</td>
           <td>{t("Created At")}</td>
+          <td>{t("Size")}</td>
           <td>{t("Action")}</td>
         </tr>
         </thead>
@@ -92,6 +93,9 @@ export default function StorageView() {
               <td>
                 {(new Date(s.createdAt)).toLocaleString()}
               </td>
+              <td>
+                {(s.currentSize/1024/1024).toFixed(2)} / {s.maxSize/1024/1024} MB
+              </td>
               <td>
                 <button className={"btn btn-square"} type={"button"} onClick={() => {
                   const dialog = document.getElementById(`confirm_delete_dialog_${s.id}`) as HTMLDialogElement;