Visualize the ingested HAProxy request logs in Grafana.
- add a `richie-postgres` datasource connecting to the Richie DB over the
local Unix socket (/run/postgresql; pg_hba trust for user richie)
- order grafana after postgresql.service
- add the "HAProxy Requests" dashboard: request rate by backend, response
-time percentiles (p50-p99), top user-agents/IPs/endpoints, status mix
Richie