ci: proper Agiliton deployment with health checks, rollback, smoke tests

- docker-compose.yml in repo (replaces inline generation in CI)
- /health nginx endpoint for container health checks
- HEALTHCHECK directive in Dockerfile
- CI pipeline: build → deploy → health check → smoke test → rollback on failure
- Smoke tests verify /health, /en/, /de/ after deploy
- Automatic rollback to previous image on health/smoke failure
- workflow_dispatch with force_deploy option
- Deploy-guard audit logging

IFK-6

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

docker-compose.yml

@@ -0,0 +1,15 @@
+services:
+  internetforkids:
+    image: gitea.agiliton.internal:3000/christian/internetforkids:latest
+    container_name: internetforkids
+    restart: unless-stopped
+    ports:
+      - "3006:80"
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:80/health"]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 10s
+    labels:
+      - "com.centurylinklabs.watchtower.enable=true"