feat: add listmonk mailing list service

group_vars/all/domains.yml

@@ -25,6 +25,7 @@ subdomains:
   bytestash: "snippets.{{ primary_domain }}"  # ByteStash code snippets
   gotify: "gotify.{{ primary_domain }}"  # Gotify notifications
   gotify_assistant: "gotify-assistant.{{ primary_domain }}"  # iGotify iOS assistant
+  listmonk: "listmonk.{{ secondary_domain }}"  # Listmonk mailing list
 
 # Email domains for notifications
 email_domains:

group_vars/docker/services.yml

@@ -6,7 +6,7 @@ service_categories:
   development: ["gitea", "bytestash"]
   media: ["audiobookshelf", "calibre", "hoarder", "manyfold"]
   productivity: ["paperlessngx", "baikal", "syncthing", "heyform", "dawarich", "obsidian-livesync"]
-  communication: ["gotosocial"]
+  communication: ["gotosocial", "listmonk"]
   monitoring: ["glance", "changedetection", "appriseapi", "gotify", "cronmaster"]
 
 # Common service configuration