Make expandable folder rows clearly distinguishable and allow clicking the
left-side toggle zone to expand/collapse folders instead of selecting them.
- Add is-expandable class and data-state-key to expandable rows
- Extract toggleFolderBrowserState helper for reuse
- Extract isFolderBrowserToggleZoneClick to detect toggle-zone clicks
- Adjust toggle button width/positioning via CSS for expandable rows
- Apply box-sizing: border-box to folder browser toggle
Dariusz L
f94abe1489