Summary

• Compact the General settings sound controls into one collapsed Sound row with a short status badge.
• Move background music and notification sound selectors into an expandable three-row list.
• Hide preview buttons when a sound is off, use the shared Play icon, and add responsive styling to avoid narrow-window overflow.
• Add English, Simplified Chinese, and Traditional Chinese strings for the new Sound row.

Validation

• npm --prefix desktop/frontend run typecheck
• npm --prefix desktop/frontend run check:css
• git diff --check
• Browser verification: collapsed status badge, expanded three-row sound list, and 390px viewport without horizontal overflow.

Related

• Related to feat: generative background music & notification sound system #3588; this PR refines the current main-v2 settings UI for the sound controls.