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

.yamllint

@@ -0,0 +1,23 @@
+---
+extends: default
+
+ignore: |
+  .claude/
+  collections/ansible_collections/
+
+rules:
+  line-length:
+    max: 160
+  truthy:
+    allowed-values: ['true', 'false']
+  document-start:
+    level: warning
+  braces:
+    min-spaces-inside: 0
+    max-spaces-inside: 1
+  comments:
+    min-spaces-from-content: 1
+  comments-indentation: disable
+  octal-values:
+    forbid-implicit-octal: true
+    forbid-explicit-octal: true