ansible: monitoring with Prometheus, Loki and Grafana

Nothing watched the servers: tonight's asxpio crash loop was found by
hand. On asxpio-ops, Prometheus (30 days), Loki (14 days) and Grafana
at gf.asxp.io (WireGuard only), with blackbox_exporter probing every
service from outside and postgres_exporter. On both hosts node_exporter
and cAdvisor on the VPC address, and Alloy shipping container logs, the
journal and Traefik's access log to Loki over the VPC.

Traefik and Forgejo expose their metrics; restic and the bucket replica
record their last success for node_exporter. Dashboards: an overview as
home, plus hosts, containers, Traefik, probes, Postgres and logs.
Alerts by email to me@asxp.io: host or service down, certificate under
14 days, disk or memory nearly full, a container restart-looping,
Postgres down, backup or replica stale.

Assisted-by: Claude:opus-5-5

ansible/roles/monitoring/templates/alerting.yaml.j2

@@ -0,0 +1,17 @@
+apiVersion: 1
+contactPoints:
+  - orgId: 1
+    name: email
+    receivers:
+      - uid: email-me
+        type: email
+        settings:
+          addresses: {{ monitoring_alert_email }}
+          singleEmail: true
+policies:
+  - orgId: 1
+    receiver: email
+    group_by: [alertname, host]
+    group_wait: 1m
+    group_interval: 5m
+    repeat_interval: 4h