Add dashboards and alerts as code, mark Phase 6 done

Dashboards: observability/dashboards/generate.py (Grafana Foundation SDK)
writes k8s/grafana/dashboards/*.json -- a RED dashboard per HTTP service
and a system overview -- shipped through a file provider and
configMapGenerators, so `kubectl apply -k k8s/` rebuilds them. Verified by
deleting Grafana and its volume and re-applying. Adds tracesToMetrics to
the Tempo datasource.

Alerts: Prometheus rule files delivering to Alertmanager, under a
labels/annotations contract enforced by observability/alerts/check_contract.py,
with runbooks in docs/runbooks/.

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

k8s/grafana/kustomization.yaml

@@ -7,9 +7,18 @@ resources:
   - service.yaml
   - ingress.yaml
 
-# Datasources only, as in the Ansible role. Dashboard provisioning is the
-# Phase 6 deliverable and belongs in this directory.
 configMapGenerator:
   - name: grafana-datasources
     files:
       - datasources.yml
+  - name: grafana-dashboards-provider
+    files:
+      - dashboards-provider.yml
+  - name: grafana-dashboards
+    files:
+      - dashboards/overview.json
+      - dashboards/red-fraud.json
+      - dashboards/red-gateway.json
+      - dashboards/red-ledger.json
+      - dashboards/red-sanctions.json
+      - dashboards/red-insights.json