Rework toasts for readability ...

Replace translucent state-tinted backgrounds with an opaque
panel: state color now lives on the border, icon, title and
progress bar only. Body text is lighter and one size larger,
padding is more generous, and the panel gains the same
elevation shadow as dropdowns and popovers.

Add light border radius across components ...

- New tokens: $border-radius-sm (3px controls), $border-radius-md
  (6px panels), $border-radius-pill (switch track)
- Apply via hard_panel and per-component: buttons, inputs, tabs,
  range thumb, checkbox, switch, chips, avatars, dropdown/popover/
  tooltip panels, modal, toast, file upload, input group, code examples
- Drawer stays sharp (flush to screen edge)

Quieten card, modal, drawer and toast accents ...

- Mute frames: base card, modal panel, drawer and default toast
  borders go from full-brightness to border-color-muted
- Replace inverted title bars (card, modal, drawer) with plain
  uppercase typography
- state_panel: state color now reads on the border and title text
  instead of a solid title bar

Redesign toast UX: compact layout, progress bar, title-only mode ...

- Replace heavy colored header strip with inline icon+title header
- Add thin bottom progress bar showing remaining lifetime
- Support title-only compact single-line toasts (no text = no body padding)
- Increase tinted background opacity from 0.06 to 0.18 for visibility
- Fix vanilla toast defaults: all variants now use lifetime=4000, alone=true
- Add demo buttons for title-only variants in both vanilla and Vue demos
- Remove hover effect from toast close button
- Adjust close button position (top: 5px) and progress bar margin (1px)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Polish cards lists and toasts

Modernize Sass build pipeline

Add navigation overlays components

Scaffold GNexus UI kit