- 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>

- Add navi/mcp/ui_server.py: FastMCP streamable_http server on port 8001
  exposing render_component(component_name, payload, session_id).
- Start server in main lifespan before container creation so McpManager can
  connect; wire orchestrator once container is ready; clean up on shutdown.
- Add env settings NAVI_UI_MCP_ENABLED/HOST/PORT.
- Add mcp_servers.d/navi_ui.json config with the 'ui' tool group.
- Frontend: dispatch ui_component websocket event, store in chat.js, render
  placeholder UiComponentCard inside AssistantMessage.vue.
- Unit tests for ui_server tool and chat.onUiComponent.

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

- Vitest + @vue/test-utils + happy-dom setup
- api/index.test.js: 8 tests for fetch wrapper, verbs, errors, FormData
- stores/chat.test.js: 23 tests for buildMessageList, WS handlers, load/clear
- stores/sessions.test.js: 6 tests for fetch, create, delete, pin, preview
- stores/profiles.test.js: 3 tests for fetch, auto-select, lookup
- composables/useWebSocket.test.js: 7 tests with MockWebSocket
- Export buildMessageList from chat store so tests can verify message parsing
- Update docs/testing.md with webclient stack, layout, and commands

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