Replace the grep-docker-logs notifier panel with a per-node UP/DOWN stat
driven by the app's new tag=heartbeat log line (count_over_time over 20m;
0 beats => DOWN/red). Update the README now that the app emits heartbeats.
A central Grafana + Loki stack (on beta) fed by a Grafana Alloy agent on
every node, replacing the old SSH-tailed single-host scripts/dashboard.py.
- docker-compose.yml: central Loki (mesh-only :3100) + Grafana (Caddy-fronted)
- loki/config.yml: single-binary, filesystem storage, 30-day retention
- alloy/config.alloy + docker-compose.agent.yml: per-node collector — every
container's stdout/stderr via the Docker socket, Caddy host logs, and the
app's structured JSON logs (errors/access/audit), each line tagged by node
- grafana/: auto-provisioned Loki datasource + a fleet-logs dashboard
(volume by service, error rate, upstream 429s, Caddy 5xx, notifier liveness,
live tail), with a per-node selector
- caddy-grafana.conf, README, .env.example
