Create admin settings and moved signup disable setting there

public/admin.ts

@@ -0,0 +1,22 @@
+document.addEventListener('DOMContentLoaded', () => {
+    registerDomSetting(document.getElementById('disable-signup') as HTMLInputElement);
+});
+
+const setSetting = (key: string, value: string) => {
+    const data = new URLSearchParams();
+    data.append('key', key);
+    data.append('value', value);
+    data.append('_csrf', ((document.getElementsByName('_csrf')[0] as HTMLInputElement).value));
+    fetch('/admin-panel/set-setting', {
+        method: 'PUT',
+        credentials: 'same-origin',
+        body: data,
+    });
+};
+
+const registerDomSetting = (el: HTMLInputElement) => {
+    el.addEventListener('change', () => {
+        setSetting(el.id, el.checked ? '1' : '0');
+    });
+};
+