feat: add gated Compose deploy and make inventory the host source of truth

Keep sanitized Compose sources in-repo with a confirmation-gated Ansible
playbook, add repo-wide validation, tighten runbook ownership/STOP/review
metadata, and archive stale research docs.

Co-authored-by: Cursor <cursoragent@cursor.com>

ansible/roles/compose_deploy/defaults/main.yml

@@ -0,0 +1,8 @@
+---
+# Allowlist of compose/ projects this playbook may deploy. A host may only
+# reference a project listed here (see tasks: "Require a repo compose project").
+compose_repo_projects:
+  - vaultwarden
+  - pdns
+  - adguardhome
+  - unifi