Add monitoring to hydra demo (#2161)

<!-- Describe your change here -->

Adding a minimal Prometheus + Grafana monitoring setup for Hydra nodes,
including panels for insight into the node's activity during demo.

**Acknowledgment:** This dashboard is largely based on the work
originally done by @jmagan. Thanks for laying the groundwork! 🙏

---

<!-- Consider each and tick it off one way or the other -->
* [X] CHANGELOG updated or not needed
* [X] Documentation updated or not needed
* [X] Haddocks updated or not needed
* [X] No new TODOs introduced or explained herafter

Author: noonio

CHANGELOG.md

@@ -79,6 +79,8 @@ when the number of persisted `StateChanged` events exceeds the configured `--per
 - Don't keep around invalid transactions as they could lead to stuck Head.
 
 
+- Add grafana monitoring to hydra nix and docker demos.
+
 ## [0.22.2] - 2025-06-30
 
 * Fix wrong hydra-script-tx-ids in networks.json

demo/docker-compose.yaml

@@ -1,6 +1,6 @@
 services:
   cardano-node:
-    image: ghcr.io/intersectmbo/cardano-node:10.2
+    image: ghcr.io/intersectmbo/cardano-node:10.4.1
     volumes:
       - ./devnet:/devnet
     environment:
@@ -189,11 +189,27 @@ services:
     command:
     - --config.file=/etc/prometheus/prometheus.yml
     volumes:
-    - ./prometheus.yml:/etc/prometheus/prometheus.yml:ro
+    - ./prometheus/docker/prometheus.yml:/etc/prometheus/prometheus.yml:ro
     networks:
       hydra_net:
         ipv4_address: 172.16.238.5
 
+  grafana:
+    image: grafana/grafana:latest
+    container_name: grafana
+    ports:
+      - "3000:3000"
+    environment:
+      - GF_PATHS_PROVISIONING=/etc/grafana/provisioning
+      - DS_PROMETHEUS=prometheus
+    volumes:
+      - "./grafana/docker/datasources.yml:/etc/grafana/provisioning/datasources/datasources.yml"
+      - "./grafana/docker/dashboard.json:/var/lib/grafana/dashboards/dashboard.json"
+      - "./grafana/docker/default.yaml:/etc/grafana/provisioning/dashboards/default.yaml"
+    networks:
+      hydra_net:
+        ipv4_address: 172.16.238.8
+
 networks:
   hydra_net:
     driver: bridge