feat(global_defaults): add root.shell to system schema and normalization

roles/configuration/tasks/users.yml

@@ -11,7 +11,7 @@
 
 - name: Set root shell
   ansible.builtin.command: >-
-    {{ chroot_command }} /usr/sbin/usermod --shell {{ system_cfg.root.shell | default('/bin/bash') }} root
+    {{ chroot_command }} /usr/sbin/usermod --shell {{ system_cfg.root.shell }} root
   register: configuration_root_shell_result
   changed_when: configuration_root_shell_result.rc == 0
 

roles/global_defaults/defaults/main.yml

@@ -87,6 +87,7 @@ system_defaults:
   users: []
   root:
     password: ""
+    shell: "/bin/bash"
   luks:
     enabled: false
     passphrase: ""

roles/global_defaults/tasks/_normalize_system.yml

@@ -84,6 +84,7 @@
       users: "{{ system_raw.users | default([]) }}"
       root:
         password: "{{ system_raw.root.password | string }}"
+        shell: "{{ system_raw.root.shell | default('/bin/bash') | string }}"
       # --- LUKS disk encryption ---
       luks:
         enabled: "{{ system_raw.luks.enabled | bool }}"