fix: null-safe doConnect for removed setup fields; move logout to settings with confirm; clean sidebar buttons

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ui.js

@@ -83,6 +83,10 @@ export function _pickTheme(id) {
   _renderThemePicker();
 }
 export function closeSettings() { document.getElementById('settings-modal').classList.remove('open'); }
+export async function confirmDisconnect() {
+  const ok = await showConfirm('Abmelden', 'Wirklich abmelden? Alle lokalen Einstellungen werden gelöscht.', 'Abmelden');
+  if (ok) { closeSettings(); window.disconnect(); }
+}
 export function saveSettings() {
   const pass = document.getElementById('s-pass').value;
   S.cfg.url       = document.getElementById('s-url').value.trim().replace(/\/$/,'');