Melody editor: audio feedback stops working on Firefox

Describe the bug

When using keyboard controls to edit a melody, the sound preview in the melody editor usually stops working after a few sounds. The console shows "Auto-suspended Audio Context". The simulator still plays sounds successfully, but the melody editor won't work again (won't play sounds) without a page reload.

To Reproduce
Steps to reproduce the behavior:

1. It doesn't matter if you have the keyboard controls setting on or off (if it is off, you will need to click to open the melody editor first)
2. Open a melody editor with keyboard or mouse controls
3. Tab to edit the melody
4. Use arrow keys to adjust
5. You should get audio feedback for each one
6. In reality you get a few and they it stops working
7. See console
8. The "play" button in the editor also stops working
9. The sounds in the simulator continue to work

Expected behavior
Preview sounds should continue to function.

Screenshots
Loom demo video here

micro:bit version (please complete the following information):
N/A

Desktop (please complete the following information):

• OS: Win 11
• Browser: Firefox 145.0.2 (64-bit). Can't replicate in Chrome.

Smartphone (please complete the following information):
N/A

Start by reproducing the failure in the Firefox melody editor while watching the console for “Auto-suspended Audio Context.” Compare the editor’s keyboard-preview and play-button behavior with simulator audio. Done means melody-editor preview sounds continue working without a page reload, including after repeated keyboard adjustments.