Port the observability platform to k3s and ship czy logs to it

k8s/ is now a faithful port of the mentor's Ansible Grafana stack
(Prometheus, Alertmanager, Loki, Tempo, Alloy, Grafana, node-exporter)
for the ledgerline-observability namespace on falken: same versions and
configs, one *.vione.cloud ingress per tool behind Traefik basic auth,
secrets generated by create-secrets.sh into gitignored files.

Two fixes over the Ansible role, both verified live: Tempo's
metrics-generator needs traces_storage or it runs no processors, and
Prometheus needs exemplar-storage to keep exemplars.

Ledgerline stays on czy; an Alloy agent in the Traefik override ships
its container logs to Loki. Roadmap and CLAUDE.md now point at k8s/.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitignore

@@ -3,6 +3,8 @@ __pycache__/
 *.pyo
 .pytest_cache/
 .env
+.env.observability
+k8s/.credentials
 *.egg-info/
 .DS_Store
 venv/