feat(26-01): implement create custom mix navigation

- Replace TODO console.log with actual navigation
- Open JamTrack editor at /jamtracks/{id} in new tab
- Use noopener,noreferrer for security best practices

jam-ui/src/components/client/JKSessionJamTrackPlayer.js

@@ -849,7 +849,7 @@ const JKSessionJamTrackPlayer = ({
                 </div>
                 <div style={{ textAlign: 'right' }}>
                   <a
-                    onClick={() => console.log('TODO: Open custom mix creator')}
+                    onClick={() => window.open(`/jamtracks/${jamTrack?.id}`, '_blank', 'noopener,noreferrer')}
                     style={{
                       fontSize: '12px',
                       color: '#007aff',