feat(configuration): multi-backend networking, bind by match not MAC

roles/configuration/defaults/main.yml

@@ -1,5 +1,3 @@
 ---
-# Network configuration dispatch - maps OS name to the task file
-# that writes network config. Default (NetworkManager) applies to
-# all OSes not explicitly listed.
-configuration_network_task_map: {}
+# Network backend is detected per host from the target rootfs in network.yml;
+# no static map needed.