Replace full innerHTML re-render with incremental DOM updates:
- renderedDisks map tracks what's already in the DOM
- On refresh: only update diskProgress_KEY and diskBtns_KEY elements
- Full card re-render only on first appearance or state/disk_id change
- If an edited disk disconnects: toast error, panel removed cleanly
- openPanels Set persists panel open state across partial updates
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Michael Chus
478f5928d4