Add listmonk newsletter role and Dex client

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

.gitmodules

@@ -124,3 +124,6 @@
 [submodule "roles/ericomeehan.grafana"]
 	path = roles/ericomeehan.grafana
 	url = git@gitea.eom.dev:DevOps/ansible-role-grafana.git
+[submodule "roles/ericomeehan.listmonk"]
+	path = roles/ericomeehan.listmonk
+	url = git@gitea.eom.dev:DevOps/ansible-role-listmonk.git

listmonk.yaml

@@ -0,0 +1,11 @@
+- name: Deploy listmonk
+  hosts: alpha-control-plane
+  become: true
+  vars_files:
+    - ../secrets.yaml
+  roles:
+    - role: ericomeehan.listmonk
+      # listmonk_admin_password and listmonk_smtp_password come from Vault as-is.
+      vars:
+        listmonk_db_password: "{{ listmonk_postgresql_password }}"
+        listmonk_oidc_client_secret: "{{ listmonk_dex_client_secret }}"