feat: add CLI Viewer Page with multi-pane layout and state management

- Implemented the CliViewerPage component for displaying CLI outputs in a configurable multi-pane layout.
- Integrated Zustand for state management, allowing for dynamic layout changes and tab management.
- Added layout options: single, split horizontal, split vertical, and 2x2 grid.
- Created viewerStore for managing layout, panes, and tabs, including actions for adding/removing panes and tabs.
- Added CoordinatorPage barrel export for easier imports.

ccw/frontend/src/pages/index.ts

@@ -27,10 +27,10 @@ export { ReviewSessionPage } from './ReviewSessionPage';
 export { McpManagerPage } from './McpManagerPage';
 export { EndpointsPage } from './EndpointsPage';
 export { InstallationsPage } from './InstallationsPage';
-export { ExecutionMonitorPage } from './ExecutionMonitorPage';
 export { RulesManagerPage } from './RulesManagerPage';
 export { PromptHistoryPage } from './PromptHistoryPage';
 export { ExplorerPage } from './ExplorerPage';
 export { GraphExplorerPage } from './GraphExplorerPage';
 export { CodexLensManagerPage } from './CodexLensManagerPage';
 export { ApiSettingsPage } from './ApiSettingsPage';
+export { CliViewerPage } from './CliViewerPage';