Add repo foundation: proxmox/lxc/vms groups, ansible.cfg, collections, lint configs

- inventory: add proxmox host, lxc and vms groups, critical_services per host
- retarget bootstrap and time-region to ubuntu:rocky so the Proxmox host is untouched
- add ansible.cfg, collections/requirements.yml, .gitignore, .yamllint, .ansible-lint
- remove stale root new_lxc.yml duplicate and the Nextcloud upgrade playbook

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JEczyvRjfakkiDNkbZA7PR

playbooks/update_system.yml

@@ -1,3 +1,4 @@
+---
 - name: Check Host Availability
   hosts: all
   gather_facts: false
@@ -43,4 +44,4 @@
       ansible.builtin.dnf:
         name: "*"
         state: latest
-        update_cache: true
+        update_cache: true