feat: add Docker infrastructure for 8-node cluster topology (2 central + 3 sites)

Multi-stage Dockerfile with NuGet restore layer caching, per-node appsettings
with Docker hostnames, shared bridge network with infra services, and
build/deploy/teardown scripts. Ports use 90xx block to avoid conflicts.

docker/deploy.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+
+echo "=== ScadaLink Docker Deploy ==="
+
+# Build image (creates network if needed)
+"$SCRIPT_DIR/build.sh"
+
+echo ""
+echo "Deploying containers..."
+docker compose -f "$SCRIPT_DIR/docker-compose.yml" up -d --force-recreate
+
+echo ""
+echo "Container status:"
+docker compose -f "$SCRIPT_DIR/docker-compose.yml" ps
+
+echo ""
+echo "Access points:"
+echo "  Central UI (node A): http://localhost:9001"
+echo "  Central UI (node B): http://localhost:9002"
+echo "  Health check:        http://localhost:9001/health/ready"
+echo "  CLI contact points:  akka.tcp://scadalink@localhost:9011"
+echo "                       akka.tcp://scadalink@localhost:9012"
+echo ""
+echo "Logs: docker compose -f $SCRIPT_DIR/docker-compose.yml logs -f"