- Add navi_ui MCP group to realtor profile tools.
- Document card_grid payload shape in realtor system prompt.
- Add card_grid schema validation in navi/mcp/ui_server.py.
- Implement CardGrid.vue: 4-card responsive grid, image/meta/description,
  modal with full details and actions on click.
- Render UI components via dynamic component in UiComponentCard.vue.
- Tests: card_grid payload validation, chat store handler, CardGrid rendering
  and modal open.

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