feat: Voice-Auswahl aus ElevenLabs-Account in den TTS-Einstellungen

Dropdown mit den Account-Stimmen (GET /tts-settings/voices/available)
plus Warnung, wenn die gespeicherte Voice-ID nicht im Account existiert
— so fällt eine ungültige Stimme (Ursache der fehlenden sv-Audios)
sofort auf statt still fehlzuschlagen.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/pages/Settings.jsx

@@ -66,6 +66,7 @@ function PipelineSettings() {
 
 export default function Settings() {
   const [rows, setRows] = useState({});   // language → settings
+  const [voices, setVoices] = useState(null); // null = lädt/nicht verfügbar
   const [saving, setSaving] = useState(null);
   const [msg, setMsg] = useState(null);
   const [error, setError] = useState(null);
@@ -78,7 +79,10 @@ export default function Settings() {
       setRows(map);
     } catch (e) { setError(e.message); }
   }
-  useEffect(() => { load(); }, []);
+  useEffect(() => {
+    load();
+    apiFetch('/tts-settings/voices/available').then(setVoices).catch(() => setVoices(null));
+  }, []);
 
   function update(lang, patch) {
     setRows(r => ({ ...r, [lang]: { ...(r[lang] || { language: lang }), ...patch } }));
@@ -132,8 +136,25 @@ export default function Settings() {
                 <div className="grid grid-cols-1 sm:grid-cols-2 gap-3">
                   <label className="text-sm">
                     <span className="block text-xs font-semibold text-slate-500 uppercase tracking-wide mb-1">Voice-ID</span>
+                    {voices?.length > 0 && (
+                      <select value={voices.some(v => v.voice_id === s.voice_id) ? s.voice_id : ''}
+                        onChange={e => e.target.value && update(lang.code, { voice_id: e.target.value })}
+                        className="w-full border border-slate-300 rounded-lg px-3 py-1.5 text-sm mb-1 focus:outline-none focus:ring-2 focus:ring-indigo-400">
+                        <option value="">— Stimme aus dem Account wählen —</option>
+                        {voices.map(v => (
+                          <option key={v.voice_id} value={v.voice_id}>
+                            {v.name}{v.labels?.accent ? ` (${v.labels.accent})` : ''}
+                          </option>
+                        ))}
+                      </select>
+                    )}
                     <input value={s.voice_id || ''} onChange={e => update(lang.code, { voice_id: e.target.value })}
                       className="w-full border border-slate-300 rounded-lg px-3 py-1.5 text-sm font-mono focus:outline-none focus:ring-2 focus:ring-indigo-400" />
+                    {voices?.length > 0 && s.voice_id && !voices.some(v => v.voice_id === s.voice_id) && (
+                      <span className="block text-xs text-red-500 mt-1">
+                        ⚠ Diese Voice-ID existiert nicht im ElevenLabs-Account — Audio-Generierung schlägt fehl.
+                      </span>
+                    )}
                   </label>
                   <label className="text-sm">
                     <span className="block text-xs font-semibold text-slate-500 uppercase tracking-wide mb-1">Geschwindigkeit</span>