refactor(global_defaults): add idempotency guards to normalization tasks

roles/global_defaults/tasks/hypervisor.yml

@@ -1,9 +1,12 @@
 ---
-- name: Ensure hypervisor input is a dictionary
+- name: Normalize hypervisor configuration
+  when: hypervisor_cfg is not defined
+  block:
+    - name: Ensure hypervisor input is a dictionary
       ansible.builtin.set_fact:
         hypervisor: "{{ hypervisor | default({}) }}"
 
-- name: Validate hypervisor input
+    - name: Validate hypervisor input
       ansible.builtin.assert:
         that:
           - hypervisor is mapping
@@ -12,7 +15,7 @@
         fail_msg: "hypervisor must be a dictionary and hypervisor.type must be set (e.g. libvirt|proxmox|vmware|xen|none)."
         quiet: true
 
-- name: Normalize hypervisor configuration
+    - name: Merge hypervisor defaults with input
       vars:
         merged: "{{ hypervisor_defaults | combine(hypervisor, recursive=True) }}"
       ansible.builtin.set_fact:

roles/global_defaults/tasks/system.yml

@@ -1,9 +1,12 @@
 ---
-- name: Validate raw system input types
+- name: Normalize system and disk configuration
+  when: system_cfg is not defined
+  block:
+    - name: Validate raw system input types
       ansible.builtin.include_tasks: _validate_input.yml
 
-- name: Normalize system configuration
+    - name: Normalize system configuration
       ansible.builtin.include_tasks: _normalize_system.yml
 
-- name: Normalize disk configuration
+    - name: Normalize disk configuration
       ansible.builtin.include_tasks: _normalize_disks.yml