ansible: restructure with dynamic inventory from flake

- Move playbooks/ to ansible/playbooks/
- Add dynamic inventory script that extracts hosts from flake
  - Groups by tier (tier_test, tier_prod) and role (role_dns, etc.)
  - Reads homelab.host.* options for metadata
- Add static inventory for non-flake hosts (Proxmox)
- Add ansible.cfg with inventory path and SSH optimizations
- Add group_vars/all.yml for common variables
- Add restart-service.yml playbook for restarting systemd services
- Update provision-approle.yml with single-host safeguard
- Add ANSIBLE_CONFIG to devshell for automatic inventory discovery
- Add ansible = "false" label to template2 to exclude from inventory
- Update CLAUDE.md to reference ansible/README.md for details

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ansible/playbooks/run-upgrade.yml

@@ -0,0 +1,9 @@
+---
+- name: Trigger nixos-upgrade job on all hosts
+  hosts: all
+  remote_user: root
+
+  tasks:
+    - ansible.builtin.systemd_service:
+        name: nixos-upgrade.service
+        state: started