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/databases/defaults/main.yml

@@ -0,0 +1,27 @@
+---
+# Role: databases
+# Valeurs par défaut pour PostgreSQL, Redis et MinIO
+
+services:
+  postgresql:
+    replicas: 2
+    resources:
+      requests:
+        cpu: "250m"
+        memory: "512Mi"
+      limits:
+        cpu: "1000m"
+        memory: "2Gi"
+
+# Stockages
+storage_sizes:
+  postgresql: "50Gi"
+  redis: "10Gi"
+  minio: "100Gi"
+
+# Mots de passe Vault (valeurs DUMMY — overridés par group_vars/vault.yml)
+vault_postgres_password: "DUMMY_POSTGRES_PASSWORD"
+vault_postgres_repmgr_password: "DUMMY_REPMGR_PASSWORD"
+vault_redis_password: "DUMMY_REDIS_PASSWORD"
+vault_minio_root_user: "DUMMY_MINIO_USER"
+vault_minio_root_password: "DUMMY_MINIO_PASSWORD"