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

ansible.cfg

@@ -0,0 +1,10 @@
+[defaults]
+inventory = inventories/all.yml
+host_key_checking = False
+retry_files_enabled = False
+interpreter_python = auto_silent
+callback_result_format = yaml
+forks = 10
+
+[ssh_connection]
+pipelining = True