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

.ansible-lint

@@ -0,0 +1,9 @@
+---
+profile: basic
+
+exclude_paths:
+  - .claude/
+  - collections/ansible_collections/
+
+skip_list:
+  - yaml[line-length]