PerfMon: Live system telemetry via project WebSocket

[brainit-consulting]

Summary

Adds live PerfMon telemetry streamed over the existing project WebSocket.

What’s included

• Backend emits perf_metrics using psutil (CPU, memory, run metadata)
• Frontend parses and stores telemetry in websocket state
• PerfMonPanel consumes live metrics (no extra socket)
• Dev-only mock fallback (gated by VITE_PERFMON_MOCK)
• Production shows unavailable state when telemetry is absent
• Stale payload labeling

Validation

pm --prefix ui run build

• python -m py_compile server/websocket.py
• Manual runtime verification with live agents

Notes

• Metrics are coarse and non-sensitive
• No mock data in production