HTTP 메트릭 저장

logs.http 토픽 ↓ MetricsConsumer.handleHttpLogEvent() ↓ HttpLogAggregatorService.addLog() ↓ HttpMetricsRepository.save() (실시간 UPSERT) ↓ http_metrics 테이블 metrics.system 토픽 ↓ MetricsConsumer.handleSystemMetricEvent() ↓ MetricsAggregatorService.saveSystemMetric() ↓ SystemMetricsRepository.save() ↓ system_metrics 테이블 /api/metrics/timeseries 요청 ↓ SystemMetricsRepository.getTimeseriesData() ↓ FULL OUTER JOIN (system_metrics + http_metrics) ↓ { timestamp, requests, errors, cpu, memory }