feat(deploy): Ansible provisioning for prod hosts (Stage 18)

Idempotent playbooks under deploy/ansible/ prepare both production hosts:
docker-ce + compose plugin, a non-sudo deploy service account holding the CI
deploy key, key-only sshd, default-deny ufw, fail2ban, unattended upgrades and
chrony. The main host also opens 80/443/9443 and creates the external edge
network; the tg host verifies direct Bot API egress (the no-VPN assumption).

The application is deployed separately by the prod-deploy workflow (later
phase), running as the deploy account this playbook provisions.

deploy/ansible/inventory.ini

@@ -0,0 +1,19 @@
+# Production inventory for Stage 18.
+#
+# Hosts resolve through the operator's ~/.ssh/config aliases, so HostName (public
+# IP), User and IdentityFile live there — no IPs or key paths are committed here.
+#   scrabble-main-ops -> main stack host (public IP, domain erudit-game.ru)
+#   scrabble-tg-ops   -> Telegram bot host (direct Bot API egress, no VPN)
+
+[main]
+scrabble-main-ops
+
+[tg]
+scrabble-tg-ops
+
+[prod:children]
+main
+tg
+
+[prod:vars]
+ansible_user=root