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)

Add GnActionCard, GnActionList, GnCopyButton, GnRange and GnTagInput ...

- Mirror reference component APIs and register them in the Vue plugin and index.

- Add supporting styles for action-card, list-actions, range, tag-input and .btn-icon.

- Add Vue demo mounts to cards, lists and inputs partials.

- Capture Lists section in screenshot review.

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

Sync tokens and components with Figma variables and frames ...

- Update primitive palette: add neutral-25, adjust warning-bg to #FEF3E5.
- Add full radius scale (xs/sm/md/lg/xl/2xl/full) from radius.tokens.json.
- Update semantic surfaces/borders from Mode 1 tokens.
- Realign buttons: primary dark, secondary mint, accent yellow, tertiary ghost.
- Realign badges, alerts, cards, inputs, checkbox, radio, switch, modal, toast.
- Update demo palette/utilities and style-guide docs.
- Add exported Figma frames and variables under 'figma design parts/' for reference.

Add Select, Textarea, and Card components ...

- Add _select.scss with native select wrapper and chevron.
- Extend _forms.scss with textarea styling.
- Add _cards.scss with default, filled, outlined, primary, secondary,
  elevated variants and sm/lg sizes.
- Add Vue adapters GnSelect, GnTextarea, GnCard matching gnexus-ui-kit API.
- Wire components into plugin and entry exports.
- Add demo partials for Select/Textarea and Cards.
- Update Vue example app and component coverage matrix.