docs: re-verify Node event-loop lag figures in CLAUDE.md #61

On Node 24.15 a 300 ms synchronous block showed up as only ~11 ms in the next lag window (monitorEventLoopDelay), while Bun showed 298 ms. CLAUDE.md states node reads ~151–161 ms for a 150 ms block. Re-measure on current Node (18/22/24) before relying on lag as a freeze signal, and correct CLAUDE.md and the event_loop_lag_* docs if they differ.

Deferred from PR #55 (trace producers over shared trackers).

🤖 Generated with Claude Code