refine: simplify update notifications

Open known updates directly without redundant searching or found toasts, retain failure and no-update feedback, and render the update dialog close action in red with a destructive hover state.

renderer/app.js

@@ -840,12 +840,10 @@ async function requestUpdateCheck({ forceRefresh = true } = {}) {
   if (_updateCheckBusy) return null;
   _updateCheckBusy = true;
   _syncHeaderUpdateState();
-  showCopyToast('Suche nach Updates…');
   try {
     const result = await window.api.checkForUpdate({ forceRefresh });
     if (result && result.available) {
       showUpdateBanner(result);
-      showCopyToast('Update gefunden!');
     } else if (result && result.error) {
       showCopyToast('Updateprüfung fehlgeschlagen');
     } else {
@@ -7436,7 +7434,7 @@ function setupListeners() {
     if (e.target.id === 'jobLogModal') hideJobLogModal();
   });
 
-  document.getElementById('headerUpdateBtn')?.addEventListener('click', requestUpdateCheck);
+  document.getElementById('headerUpdateBtn')?.addEventListener('click', () => requestUpdateCheck({ forceRefresh: false }));
   document.getElementById('installUpdateBtn')?.addEventListener('click', installKnownUpdate);
   document.getElementById('dismissUpdateBtn')?.addEventListener('click', handleUpdateDismiss);
   document.getElementById('updateCloseBtn')?.addEventListener('click', closeUpdateDialog);

renderer/i18n.js

@@ -582,7 +582,6 @@
     ['Speichern vor dem Beenden hat zu lange gedauert', 'Saving before quitting took too long'],
     ['Stoppt nach aktiven Uploads...', 'Stopping after active uploads...'],
     ['Suche nach Aktualisierungen…', 'Checking for updates…'],
-    ['Suche nach Updates…', 'Checking for updates…'],
     ['System wird heruntergefahren in', 'System will shut down in'],
     ['Übernehmen', 'Apply'],
     ['Übersprungen', 'Skipped'],

renderer/styles.css

@@ -2405,14 +2405,14 @@ select.hs-input { max-width: none; width: auto; min-width: 140px; }
   border: 1px solid transparent;
   border-radius: 6px;
   background: transparent;
-  color: var(--text-dim);
+  color: var(--danger);
   cursor: pointer;
 }
 
 .update-close-button:hover {
-  border-color: var(--border);
-  background: var(--bg-active);
-  color: var(--text);
+  border-color: transparent;
+  background: var(--danger);
+  color: #000;
 }
 
 .update-close-button svg {