DevTools: Implement Rich Live display for real-time CLI progress

Summary

Implement Rich Live display for real-time progress visualization in CLI when tools are running.

Context

The WebSocket infrastructure for streaming tool events is already complete:

• api/websocket.py (263 lines) - WebSocket endpoint, event streaming ✅
• api/websocket_client.py (468 lines) - Client with progress callbacks ✅
• core/events/bus.py (421 lines) - EventBus with pattern routing ✅
• core/events/types.py - FileChangedEvent, ToolProgressEvent, ToolCompletedEvent ✅

Gap

CLI currently:

• ✅ Sends commands via WebSocket
• ✅ Receives ToolProgressEvent and ToolCompletedEvent
• ⚠️ Displays results after completion (static, not live)

Missing: Rich Live visualization that shows real-time progress bars during tool execution.

Proposed Implementation

Files to create:

• output/ui/live_progress.py - Rich Live context manager
• output/ui/progress_widget.py - Tool progress widget

Acceptance Criteria

• [ ] Progress bar shows file processing count during tool execution
• [ ] Multiple tools show concurrent progress bars
• [ ] Tool completion updates progress bar to complete state
• [ ] Graceful degradation when terminal doesn't support Live display

Architecture Reference

See packages/airia-devtools/src/airia_devtools/ARCHITECTURE.md v5.1.0 for target architecture.

Priority

LOW - Current static display is functional for MVP.

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Generated by architecture compliance review (2026-01-08)