Add Grafana dashboards for monitoring various services

- Created a new dashboard for NGINX monitoring with panels for status, active connections, request rates, and connection drop ratio.
- Added a Node dashboard to monitor CPU usage, memory usage, disk I/O, and network traffic.
- Introduced a Playout dashboard to track service status, mode, FFmpeg restarts, and scrape duration.
- Implemented a PostgreSQL dashboard featuring active connections, database size, transaction rates, and cache hit ratio.
- Developed a Prometheus dashboard to visualize scrape duration, targets status, and rule evaluation metrics.
- Established a Redis dashboard to monitor connected clients, memory usage, command latency, and keyspace statistics.

docs/MONITORING.md

@@ -57,7 +57,6 @@ Config: `monitoring/prometheus/prometheus.yml` (15s scrape interval)
 See detailed scripts for querying Prometheus scrape targets:
 
 - [Linux/macOS](./infrastructure/monitoring/prometheus_curl.md)
-- [Windows](./infrastructure/monitoring/prometheus_curl_win.md)
 
 ## Key Metrics