feat: add adaptive metrics and circuit breaker trips tracking

Added metrics tracking for:
- circuit_breaker_trips_total: Incremented when circuit opens
- adaptive_health_status: 1 if healthy (not in aggressive mode), 0 otherwise
- adaptive_event_rate: Current events per second

Added methods to AdaptiveTimeoutCalculator:
- getEventRate(): Returns current event rate in events/second
- isHealthy(): Returns true if not in aggressive mode

Metrics are updated on each buffer flush when adaptive timeout is enabled.

src/Utils/prometheus-metrics.ts

@@ -1958,6 +1958,19 @@ export function recordBufferFinalFlush(): void {
 	}
 }
 
+/**
+ * Update adaptive system metrics
+ * Used by event-buffer.ts to report adaptive timeout health and event rate
+ */
+export function updateAdaptiveMetrics(eventRate: number, isHealthy: boolean): void {
+	try {
+		metrics.adaptiveEventRate?.set({}, eventRate)
+		metrics.adaptiveHealthStatus?.set({}, isHealthy ? 1 : 0)
+	} catch {
+		// Metrics not initialized, ignore silently
+	}
+}
+
 // ============================================
 // Global Instance
 // ============================================