Full LivePage implementation with 60/40 split layout:
- Left column: Activity Timeline with color-coded event cards (run.started, run.completed, new_best_found, cache_hit, run.failed), event type filtering, and auto-scroll toggle
- Right column: Leaderboard table with sortable columns, best-run highlighting, and status badges; Steering Controls with pause/resume/stop (with confirmation dialogs), progress bar, token counter, cost estimate, and cache hit rate
- WebSocket integration with exponential backoff reconnect, connection status indicator, and experiment subscription
- 35 tests covering loading/error states, WebSocket events, timeline filtering, leaderboard updates, progress tracking, and steering control interactions
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