Add overlay components: Modal, Drawer, Toast system ...

- Add SCSS for modals, drawers and toasts with VMK design tokens.
- Add GnModal and GnDrawer Vue adapters with focus trap, Escape close and teleport.
- Add browser Toasts helper and GnToastProvider + useToast composable.
- Wire overlays into plugin, Vue entry and browser bundle.
- Add demo partials for Modal, Drawer and Toast.
- Update component coverage and project notes.

Integrate user-provided SVG icon set ...

- Extract Icons_svg.zip into public/assets/icons/svg/ (967 icons).
- Replace stroke="black" and fill="black" with currentColor in all SVGs
  so icons inherit text color.
- Build public/assets/icons/index.json mapping clean names to SVG paths.
- Add src/js/components/icon-helper.js for async inline SVG loading.
- Add src/scss/components/_icons.scss with base icon styles.
- Import icons component styles into kit.scss.

Build, Vue example build, and Playwright smoke test still pass.