monitoring: keep Loki chunks in S3, 90 days of logs and metrics

ops has 12 GB free on a 38 GB disk and the Traefik access log alone
is ~600 MB, so logs can't grow there. From 2026-11-14 Loki writes
chunks and index to Hetzner Object Storage (asxpio-loki-main, hel1)
with the existing project key, passed through loki.env and
-config.expand-env. Today's filesystem period ages out by retention.

Log retention goes from 14 to 90 days. Prometheus metrics are small
(~20 MB so far) and stay local, now for 90 days instead of 30.

Assisted-by: Claude:opus-5-5

ansible/inventory/group_vars/all/s3.yaml

@@ -17,6 +17,7 @@ s3_bucket_terraform_main: asxpio-terraform-main
 s3_bucket_terraform_repl: asxpio-terraform-repl
 s3_bucket_backups_main: asxpio-backups-main
 s3_bucket_backups_repl: asxpio-backups-repl
+s3_bucket_loki: asxpio-loki-main
 
 # S3 Buckets to mount on servers (non-replication only)
 s3_buckets: