Drag-and-drop:
- 3-zone drop indicator for groups and parent notes (files with children):
top 25% = drop above, middle 50% = drop into, bottom 25% = drop below
- 2-zone for regular files/separators/spacers (unchanged)
- 'Drop into' shows background highlight instead of border line
- Circular reference guard: can't drop a group into itself or descendants
⋯ button:
- No visible button chrome when not hovered (no border, no background)
- Subtle opacity (0.6) at rest, full opacity on hover
- Hover shows text color change only, no background highlight
olivier