Add service registry, shared roles and unified reverse proxy

Collect the facts about all 14 services -- VMID, node, address, ports,
domain, pinned images, resources, backup and monitoring participation --
into group_vars/all/services.yml. Values are taken from the existing
playbooks; gaps are marked null rather than invented.

Replace reverse-proxy-{gitea,vaultwarden,grimmory}.yml with a single
playbook iterating over registry entries that declare a domain. It keeps
every check the three had, preserves grimmory's richer Caddy block
byte-for-byte, and restarts Caddy once when any site changed instead of
up to three times. Verified with --check --diff against ru-vps: ok=6
changed=0, so it reproduces the current Caddyfile exactly.

Add two roles factoring out the skeleton duplicated across the pve-*
playbooks: lxc_docker_host (packages, /dev/fuse assertion, fuse-overlayfs
storage driver, UFW baseline) and compose_service (compose file, systemd
unit, config validation, health check). They are not wired into any
playbook yet -- migrating a live service is a separate, per-service step;
compose_service/README.md shows the Gitea example and spells out what
actually changes on the host.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GTocXkGUUazHdKKd3r9k71

ansible/roles/compose_service/handlers/main.yml

@@ -0,0 +1,7 @@
+---
+# Юнит должен быть перечитан ДО задачи enable/start, поэтому вызывающая роль
+# сразу после установки юнита делает `meta: flush_handlers`.
+- name: Reload systemd for compose services
+  ansible.builtin.systemd:
+    daemon_reload: true
+  listen: compose_service_daemon_reload