Split the sway conf files list into two variables so configs can be appended without having to re-define the default list.

ansible/roles/sway/defaults/main.yaml

@@ -1,4 +1,4 @@
-sway_conf_files:
+default_sway_conf_files:
   - background
   - framework_input
   - base_hotkeys

ansible/roles/sway/tasks/peruser.yaml

@@ -47,7 +47,7 @@
     mode: 0600
     owner: "{{ account_name.stdout }}"
     group: "{{ group_name.stdout }}"
-  loop: "{{ sway_conf_files }}"
+  loop: "{{ sway_conf_files|default([]) + default_sway_conf_files }}"
 
 - import_tasks: tasks/peruser_freebsd.yaml
   when: 'os_flavor == "freebsd"'