feat(k8s): add defaults/main.yml, meta/main.yml for all 27 roles + 4 helm templates

- Added defaults/main.yml with production-ready values for all 27 Ansible roles
- Added meta/main.yml with role dependencies (DAG: prereq → namespaces → storage → traefik → cert-manager → services)
- Created 4 missing Helm templates: flink-deployment, kafka-cluster, smartapp-web, smartapp-api
- Fixed YAML syntax error in backup/tasks/main.yml (Velero backupStorageLocation)
- Updated README with domain list, dependencies diagram, and corrected Helm chart names
- All 81 YAML files pass validation

helms/roles/prerequisites/defaults/main.yml

@@ -0,0 +1,19 @@
+---
+# Role: prerequisites
+# Valeurs par défaut pour les prérequis (repositories Helm)
+
+helm_repos:
+  - name: stable
+    url: https://charts.helm.sh/stable
+  - name: bitnami
+    url: https://charts.bitnami.com/bitnami
+  - name: prometheus-community
+    url: https://prometheus-community.github.io/helm-charts
+  - name: grafana
+    url: https://grafana.github.io/helm-charts
+  - name: traefik
+    url: https://traefik.github.io/charts
+  - name: strimzi
+    url: https://strimzi.io/charts/
+  - name: jetstack
+    url: https://charts.jetstack.io