feat: dynamic DNS updater sidecar (auto-updates A + AAAA every 5min)

- update-dns.sh: detects public IPv4/IPv6, upserts CF records
- Runs on container start + every 5 minutes
- Only updates if IP actually changed (skips if unchanged)
- python:3-alpine container with curl

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

warzone/deploy/docker/docker-compose.yml

@@ -82,6 +82,18 @@ services:
     networks:
       - backend
 
+  # ─── Dynamic DNS updater (keeps A + AAAA current) ───
+  dns-updater:
+    image: python:3-alpine
+    restart: unless-stopped
+    volumes:
+      - ./update-dns.sh:/update-dns.sh:ro
+    secrets:
+      - cf_api_token
+    entrypoint: ["/bin/sh", "/update-dns.sh"]
+    environment:
+      DNS_UPDATE_INTERVAL: "300"  # 5 minutes
+
 secrets:
   cf_api_token:
     file: ./cf_api_token.txt