Show toast when download is skipped due to duplicate

Backend: set skipped:true on job when track already exists on disk.
Album downloads report "X geladen, Y bereits vorhanden" in the message.
Frontend: pollJob shows "⏭ bereits auf dem Server" instead of "✅ gespeichert"
when the job has skipped:true.

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

src/ui.js

@@ -312,7 +312,10 @@ async function pollJob(jobId) {
     const d = await res.json();
     updateJob(jobId, d.status, d.message, d.progress);
     if(d.status!=='done' && d.status!=='error') setTimeout(() => pollJob(jobId), 1500);
-    else if(d.status==='done') toast(`✅ ${S.jobs[jobId]?.title||'Track'} gespeichert!`);
+    else if(d.status==='done') {
+      const title = S.jobs[jobId]?.title || 'Track';
+      toast(d.skipped ? `⏭ "${title}" bereits auf dem Server` : `✅ ${title} gespeichert!`);
+    }
   } catch { updateJob(jobId, 'error', 'Status-Abfrage fehlgeschlagen'); }
 }