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/roles/main/tasks/main.yml

@@ -0,0 +1,18 @@
+---
+# Main stack host: public web + bot-link ports and the external 'edge' network
+# the compose stack attaches caddy to.
+
+- name: Open public web and bot-link ports
+  community.general.ufw:
+    rule: allow
+    port: "{{ item }}"
+    proto: tcp
+  loop:
+    - "80"    # HTTP (ACME challenge + redirect to HTTPS)
+    - "443"   # HTTPS (caddy edge)
+    - "9443"  # bot-link mTLS (remote bot dials in; mutual TLS gates access)
+
+- name: Ensure the external 'edge' docker network exists
+  community.docker.docker_network:
+    name: edge
+    state: present