Fix bugs from user feedback

[achimmihca]

The following issues should be fixed

• vocals isolation not working: https://discord.com/channels/957290213246390352/1204424209866952717
  • I was not able to reproduce this issue. Please re-test.
• when using four players, the song guidance/scoring isn't usable anymore. Only one player has its complete song in view, the others are partly presented: https://steamcommunity.com/app/2394070/discussions/0/3878218563604797601/
  • I was not able to reproduce this issue. Please re-test.
• golden note effect draws outside of player UI. This is very visible when using scrolling note stream and more than 3 players.
  • Reason is that the particle effect is above everything else, thus not respecting the player UI area.
    • One solution could be to create VisualElements inside the player UI area instead of using a particle system. But this has probably less optimal performance.
    • Another solution might be to do some trickery with the particle effect, something to restrict its drawing area. But not sure if this exists as needed.
    • Workaround: use sentence-by-sentence display mode

Song Editor

• AI tools and LRC import have issues: https://discord.com/channels/957290213246390352/1244049816246419537
  • I was not able to reproduce this issue. Please re-test.
• lyrics editing: https://steamcommunity.com/app/2394070/discussions/0/4337608365466525712/
  • I was not able to reproduce this issue. Please re-test.