Support prometheus metrics from infinistore

[Jeffwan]

It would be great to support Prometheus-compatible metrics in InfiniStore to improve observability and integration with standard monitoring stacks.

Use cases:

• Enable users to monitor InfiniStore performance and health via existing Grafana dashboards.
• Track cache hit/miss rates, request latencies, eviction rates, etc.
• Integrate with Kubernetes-native monitoring environments.

[tianlang-wq]

Has the metrics feature been implemented yet