Second modernization batch (reference: easystudy ui_elements):
- Toast/snackbar notifications (dark, green check) for actions — copy link.
- Mode switch: icons (horizontal bars / pin / columns) + a sliding active
indicator; fixed width so the bold active label never resizes the block.
- Appearance number fields became steppers: an editable field with centred −/+
buttons, ~20% narrower.
- Date filter: the two native date inputs are replaced by a custom range picker
— one field "Период (даты)" + a calendar popup with month nav and range
selection (circle endpoints, light band between). The native inputs stay hidden
as the source of truth so all filter/URL/chip wiring is unchanged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
