feat(ess_pro): deploy Element Server Suite Pro via K3s + Helm

Adds k3s and ess_pro roles to replace the planned Nextcloud Talk
stack. Integrates with existing Keycloak (OIDC), Garage (S3 media)
and OpenBao (secrets). Hostnames under digitalboard.ch.

roles/k3s/meta/main.yml

@@ -0,0 +1,12 @@
+---
+galaxy_info:
+  role_name: k3s
+  author: digitalboard
+  description: Install single-node K3s suitable for hosting ESS Pro
+  license: MIT
+  min_ansible_version: "2.14"
+  platforms:
+    - name: Debian
+      versions:
+        - bookworm
+dependencies: []