fix: hide quality selector when format is mp3

Quality/resolution options don't apply to audio-only output.

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

src/components/SubmitForm.tsx

@@ -225,12 +225,14 @@ export function SubmitForm({ examplePlaceholder }: { examplePlaceholder?: string
                 </select>
               </label>
 
+              {format !== 'mp3' && (
                 <label className="flex items-center gap-2">
                   <span>{t('quality')}</span>
                   <select value={quality} onChange={(e) => setQuality(e.target.value)} className={selectClass}>
                     {capabilities.availableQualities.map((q) => <option key={q}>{q}</option>)}
                   </select>
                 </label>
+              )}
             </>
           )}