refactor(standardize): remove dead code, fix inconsistencies, update docs

- Remove unused sudo_lecture.txt.j2 template (never referenced)
- Add vars_proxmox.yml and .sisyphus/ to .gitignore
- Remove redundant inner when conditions in cleanup/vmware.yml
- Standardize bootstrap_var_key usage in alpine, opensuse, void tasks
- Normalize sysctl key=value formatting (remove inconsistent spaces)
- Add vars_baremetal_example.yml to README examples list
- Remove unnecessary changed_when on set_fact in hypervisor.yml

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

roles/bootstrap/tasks/alpine.yml

@@ -3,7 +3,7 @@
   vars:
     bootstrap_alpine_packages: >-
       {{
-        lookup('vars', 'bootstrap_alpine') | reject('equalto', '') | join(' ')
+        lookup('vars', bootstrap_var_key) | reject('equalto', '') | join(' ')
       }}
   block:
     - name: Ensure chroot has resolv.conf