fix(global_defaults): enrich pre-computed system_cfg with bootstrap defaults

roles/global_defaults/tasks/system.yml

@@ -10,3 +10,30 @@
 
     - name: Normalize disk configuration
       ansible.builtin.include_tasks: _normalize_disks.yml
+
+- name: Check if pre-computed system_cfg needs enrichment
+  when: system_cfg is defined
+  ansible.builtin.set_fact:
+    _bootstrap_needs_enrichment: "{{ hostname is not defined }}"
+
+- name: Merge pre-computed system_cfg with bootstrap system_defaults
+  when:
+    - system_cfg is defined
+    - _bootstrap_needs_enrichment | default(false) | bool
+  ansible.builtin.set_fact:
+    system_cfg: "{{ system_defaults | combine(system | default({}), recursive=True) | combine(system_cfg, recursive=True) }}"
+
+- name: Derive convenience facts from pre-computed system_cfg
+  when:
+    - system_cfg is defined
+    - _bootstrap_needs_enrichment | default(false) | bool
+  ansible.builtin.set_fact:
+    hostname: "{{ system_cfg.name | default(inventory_hostname) }}"
+    os: "{{ system_cfg.os | default('') }}"
+    os_version: "{{ system_cfg.version | default('') | string }}"
+
+- name: Normalize disk configuration (pre-computed system_cfg)
+  when:
+    - system_cfg is defined
+    - install_drive is not defined
+  ansible.builtin.include_tasks: _normalize_disks.yml