deploy(backend): add prod Dockerfiles, compose stack, nginx configs, deploy scripts

Multi-stage Dockerfiles for accounts-service/configs-service/gateway, a
docker-compose.prod.yml wiring fresh Postgres+MinIO+the three services on a
private network, nginx site templates for visual.loki-code.dev (static SPA +
/api proxy) and bekend.loki-code.dev (full gateway proxy for the mod), and
idempotent setup.sh/deploy.sh scripts for the VDS.

Claude-Session: https://claude.ai/code/session_01F1M1Jic1wTSn4igUENynmZ

backend/deploy/deploy.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+# Idempotent redeploy for LoVisual. Run as: /opt/lovisual/deploy.sh
+set -euo pipefail
+
+REPO_DIR=/opt/lovisual
+FRONTEND_ROOT=/var/www/visual.loki-code.dev/html
+
+cd "$REPO_DIR"
+git pull --ff-only
+
+echo "==> Building & (re)starting backend services"
+cd "$REPO_DIR/backend"
+docker compose -f docker-compose.prod.yml up -d --build
+
+echo "==> Building frontend"
+cd "$REPO_DIR/frontend"
+npm ci
+npm run build
+
+echo "==> Syncing frontend build to $FRONTEND_ROOT"
+mkdir -p "$FRONTEND_ROOT"
+rsync -a --delete dist/ "$FRONTEND_ROOT/"
+
+echo "==> Reloading nginx"
+nginx -t
+systemctl reload nginx
+
+echo "==> Done"
+docker compose -f "$REPO_DIR/backend/docker-compose.prod.yml" ps