Get Exchange Health

{
  "generated_at": "2026-08-12T18:00:00Z",
  "thresholds": { "warn_staleness_seconds": 15, "max_staleness_seconds": 30, "window_seconds": 300, "rest_p95_ms": 5000, "error_rate": 0.2 },
  "exchanges": [{
    "exchange": "Binance", "status": "healthy", "reasons": [],
    "rest": { "requests": 15, "errors": 0, "error_rate": 0, "latency_p50_ms": 500, "latency_p95_ms": 1000 },
    "websocket": { "supported": true, "state": "connected", "reconnect_count": 1, "staleness_seconds": 2, "symbol_count": 312, "stale_symbol_count": 0, "discarded_symbol_count": 0 }
  }]
}