Update Ansible configuration and documentation to reflect new inventory structure. Migrate group_vars to inventory/group_vars/ and enhance README with updated paths for variable files, improving clarity for users.

ansible/inventory/group_vars/debian_servers.yml

@@ -0,0 +1,12 @@
+---
+# Hardened SSH settings
+debian_baseline_ssh_allow_users:
+  - admin
+
+# Example key rotation entries. Replace with your real users and keys.
+debian_ssh_rotation_users:
+  - name: admin
+    home: /home/admin
+    state: present
+    keys:
+      - "ssh-ed25519 AAAAEXAMPLE_REPLACE_ME admin@workstation"