feat(demo): add complete TSYS developer support stack demo implementation

Add full demo environment with 13 services across 4 categories:
- Infrastructure: Homepage, Docker Socket Proxy, Pi-hole, Portainer
- Monitoring: InfluxDB, Grafana
- Documentation: Draw.io, Kroki
- Developer Tools: Atomic Tracker, ArchiveBox, Tube Archivist,
  Wakapi, MailHog, Atuin

Includes:
- Docker Compose templates with dynamic environment configuration
- Deployment orchestration scripts with user ID detection
- Comprehensive test suite (unit, integration, e2e)
- Pre-deployment validation with yamllint, shellcheck
- Full documentation (PRD, AGENTS, README)
- Service configurations for all components

All services configured for demo purposes with:
- Dynamic UID/GID mapping
- Docker socket proxy security
- Health checks and monitoring
- Service discovery via Homepage labels

Ports allocated 4000-4099 range with sequential assignment.

💘 Generated with Crush

Assisted-by: GLM-4.7 via Crush <crush@charm.land>

demo/tests/integration/test_service_communication.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+# Integration test: Service-to-service communication
+
+set -euo pipefail
+
+test_grafana_influxdb_integration() {
+    # Test Grafana can reach InfluxDB
+    # This would be executed after stack deployment
+    if docker exec tsysdevstack-supportstack-demo-grafana wget -q --spider http://influxdb:8086/ping; then
+        echo "PASS: Grafana-InfluxDB integration"
+        return 0
+    else
+        echo "FAIL: Grafana-InfluxDB integration"
+        return 1
+    fi
+}
+
+test_portainer_docker_integration() {
+    # Test Portainer can reach Docker socket
+    if docker exec tsysdevstack-supportstack-demo-portainer docker version >/dev/null 2>&1; then
+        echo "PASS: Portainer-Docker integration"
+        return 0
+    else
+        echo "FAIL: Portainer-Docker integration"
+        return 1
+    fi
+}
+
+test_homepage_discovery() {
+    # Test Homepage discovers all services
+    local discovered_services
+    discovered_services=$(curl -s http://localhost:4000 | grep -c "service" || echo "0")
+    if [[ $discovered_services -ge 14 ]]; then
+        echo "PASS: Homepage service discovery"
+        return 0
+    else
+        echo "FAIL: Homepage service discovery (found $discovered_services, expected >=14)"
+        return 1
+    fi
+}
+
+# Run integration tests
+test_grafana_influxdb_integration
+test_portainer_docker_integration
+test_homepage_discovery