feat(network): make interfaces[] canonical, normalize flat fields as AWX compat

Flat network fields (bridge, ip, prefix, gateway, vlan) are now converted
into a single-entry interfaces[] list during normalization. All virtualization
tasks (proxmox, vmware, libvirt, xen) and configuration (NM, Alpine, Void)
now consume system_cfg.network.interfaces exclusively for multi-NIC support.

Also fixes: user.key -> user.keys in system_cfg output, strict list-only DNS
in example inventories, removes legacy single-MAC virtualization_mac_address
default.

roles/virtualization/tasks/vmware.yml

@@ -14,6 +14,17 @@
 
 - name: Create VM in vCenter
   delegate_to: localhost
+  vars:
+    virtualization_vmware_networks: >-
+      {%- set ns = namespace(out=[]) -%}
+      {%- for iface in system_cfg.network.interfaces -%}
+      {%- set entry = {'name': iface.bridge, 'type': 'dhcp'} -%}
+      {%- if (iface.vlan | default('') | string | length) > 0 -%}
+      {%- set entry = entry | combine({'vlan': iface.vlan | int}) -%}
+      {%- endif -%}
+      {%- set ns.out = ns.out + [entry] -%}
+      {%- endfor -%}
+      {{ ns.out }}
   community.vmware.vmware_guest:
     hostname: "{{ hypervisor_cfg.url }}"
     username: "{{ hypervisor_cfg.username }}"
@@ -53,10 +64,7 @@
             "iso_path": rhel_iso
           } ] if rhel_iso is defined and rhel_iso | length > 0 else [] )
       }}
-    networks:
-      - name: "{{ system_cfg.network.bridge }}"
-        type: dhcp
-        vlan: "{{ system_cfg.network.vlan if system_cfg.network.vlan is defined and system_cfg.network.vlan | string | length > 0 else omit }}"
+    networks: "{{ virtualization_vmware_networks }}"
   register: virtualization_vmware_create_result
 
 - name: Set VM created fact when VM was powered on during creation