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

Claude-Session: https://claude.ai/code/session_01JEczyvRjfakkiDNkbZA7PR

playbooks/ping.yml

@@ -1,7 +1,7 @@
+---
 - name: Ping all servers
   hosts: all
-  gather_facts: no
+  gather_facts: false
   tasks:
     - name: Test connectivity with ping
       ansible.builtin.ping:
-