fix(05-05): update JKPopupMediaControls to use selectDownloadState

- Replaced non-existent selectDownloadingJamTrack with selectDownloadState
- Computed downloadingJamTrack from downloadState.state
- Fixes import error preventing compilation

jam-ui/src/components/popups/JKPopupMediaControls.js

@@ -13,7 +13,7 @@ import {
   selectJamTracks,
   selectRecordedTracks,
   selectJamTrackState,
-  selectDownloadingJamTrack
+  selectDownloadState
 } from '../../store/features/mediaSlice';
 import {
   selectShowMyMixes,
@@ -34,13 +34,16 @@ const JKPopupMediaControls = ({ onClose }) => {
   const recordedTracks = useSelector(selectRecordedTracks);
   const metronome = useSelector(selectMetronome);
   const jamTrackState = useSelector(selectJamTrackState);
-  const downloadingJamTrack = useSelector(selectDownloadingJamTrack);
+  const downloadState = useSelector(selectDownloadState);
   const showMyMixes = useSelector(selectShowMyMixes);
   const showCustomMixes = useSelector(selectShowCustomMixes);
   const editingMixdownId = useSelector(selectEditingMixdownId);
   const creatingMixdown = useSelector(selectCreatingMixdown);
   const createMixdownErrors = useSelector(selectCreateMixdownErrors);
 
+  // Compute if JamTrack is currently downloading
+  const downloadingJamTrack = downloadState.state === 'downloading' || downloadState.state === 'checking' || downloadState.state === 'keying';
+
   // Redux actions
   const {
     closeMedia,