refactor(schema): rename nested dict keys and simplify validation

roles/configuration/tasks/users.yml

@@ -18,7 +18,7 @@
   changed_when: configuration_user_result.rc == 0
 
 - name: Ensure .ssh directory exists
-  when: system_cfg.user.public_key | length > 0
+  when: system_cfg.user.key | length > 0
   ansible.builtin.file:
     path: /mnt/home/{{ system_cfg.user.name }}/.ssh
     state: directory
@@ -27,10 +27,10 @@
     mode: "0700"
 
 - name: Add SSH public key to authorized_keys
-  when: system_cfg.user.public_key | length > 0
+  when: system_cfg.user.key | length > 0
   ansible.builtin.lineinfile:
     path: /mnt/home/{{ system_cfg.user.name }}/.ssh/authorized_keys
-    line: "{{ system_cfg.user.public_key }}"
+    line: "{{ system_cfg.user.key }}"
     owner: 1000
     group: 1000
     mode: "0600"