feat: add remaining reference Vue components, card variants, toolbar/repeater/activity-log/usage-meter styles and demo mounts ...

- Add GnHorizontalCard, GnUserCard, GnMetricCard, GnStatusCard, GnLoginCard,
  GnIdentity, GnActivityLog, GnToolbar, GnRouterTabs, GnRepeater, GnUsageMeter
- Extend GnTabs to support reference items API while keeping child mode
- Add card subcomponent styles: status, metric, horizontal, login, user
- Add toolbar, repeater, identity, activity-log, usage-meter styles
- Add typography token variables used by reference-compatible components
- Add Vue demo mounts for cards, data-patterns, progress, tabs, navigation-shell
- Fix GnAvatar online status class and navigation-shell footer slot
- Update screenshot config to cover skeleton and navigation-shell

Verified: npm run build, npm run test:e2e (19 passed), npm run screenshots,
npm run test:vue-adapter, figma-match (7 passed)

Polish triggers, breadcrumbs, drawer, file preview, editable icons, logos ...

- Use btn-sm for popover, tooltip, dropdown, modal-open, confirm, toast, drawer triggers.
- Use btn-md with gap for modal and confirm-popup action buttons.
- Fix left drawer: correct SCSS nesting so .drawer-left panel slides from left.
- Align breadcrumbs demo with Figma: dark surface, active pill, collapsed rows.
- Unify File Upload preview cards with static File attachment cards markup.
- Style Editable String buttons as btn-icon-only btn-sm.
- Fix 'essentials/search' icon mapping to 'essentials/zoom/search'.
- Add Logos component block from Figma frames.
- Expand screenshot section list to cover more component demos.
- All 19 e2e tests green.

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

Add Table, List, Skeleton, Tooltip, Dropdown, NavigationShell ...

- Implement Table styles + browser helper + GnTable/GnTableRow/GnTableHeader
  with sortable/selectable variants.
- Implement List styles + browser helper + GnList/GnListItem.
- Implement Skeleton placeholders + browser helper + GnSkeleton.
- Implement Tooltip styles + browser helper + GnTooltip.
- Implement Dropdown menu styles + browser helper + GnDropdown/GnDropdownItem.
- Implement NavigationShell layout + browser helper + GnNavigationShell/GnNavigationItem.
- Wire all new components into kit.scss, Vue plugin, Vue entry, and browser bundle.
- Add demo partials for every new component.
- Update docs/component-coverage.md and PROJECT_NOTES.md.
- Builds and tests pass.