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/locales/en/navigation.json

@@ -14,7 +14,9 @@
     "project": "Project",
     "history": "History",
     "orchestrator": "Orchestrator",
+    "coordinator": "Coordinator",
     "loops": "Loop Monitor",
+    "cliViewer": "CLI Viewer",
     "issues": "Issues",
     "issueQueue": "Issue Queue",
     "issueDiscovery": "Issue Discovery",
@@ -75,6 +77,8 @@
     "noExecutionsHint": "Start a CLI command to see streaming output",
     "noMessages": "Waiting for messages...",
     "noMatch": "No matching messages found",
+    "openInViewer": "Open in CLI Viewer",
+    "popOutToPage": "Pop out to full page",
     "statusBar": "{total} executions | {active} active | {errors} error | {lines} lines",
     "copy": "Copy",
     "copied": "Copied!",