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/time-region.yml

@@ -1,6 +1,6 @@
 ---
 - name: Configure timezone on all hosts
-  hosts: all
+  hosts: ubuntu:rocky
   become: true
   gather_facts: true
 
@@ -101,7 +101,7 @@
         enabled: true
 
 - name: Verify time configuration
-  hosts: all
+  hosts: ubuntu:rocky
   become: true
 
   tasks:
@@ -112,4 +112,4 @@
 
     - name: Summary
       ansible.builtin.debug:
-        msg: "{{ inventory_hostname }} ({{ ansible_virtualization_type | default('unknown') }}) - {{ check_time.stdout }}"
+        msg: "{{ inventory_hostname }} ({{ ansible_virtualization_type | default('unknown') }}) - {{ check_time.stdout }}"