Migrate CI to single-step DinD with Fabio/Consul

Replace 5-step pipeline (build/test/push/push/deploy) with single
docker:dind step that builds and deploys in-place via Docker socket.

- .woodpecker.yml: single-step DinD, 1 secret (SECRET_KEY)
- docker-compose.fabio.yml: overlay with SERVICE_* labels for Registrator
- docker-compose.yml: add ports without host bind (Fabio/Traefik routing)
- docker-compose.dev.yml: named volumes with bind driver
- Dockerfiles: install curl, HEALTHCHECK via curl /api/health
- Makefile: docker-fabio, consul-services, fabio-routes targets

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker/backend.Dockerfile

@@ -17,13 +17,16 @@ FROM base AS production
 
 ENV PYTHONUNBUFFERED=1
 
+RUN apt-get update && apt-get install -y --no-install-recommends curl \
+    && rm -rf /var/lib/apt/lists/*
+
 COPY --from=build /usr/local/lib/python3.11/site-packages /usr/local/lib/python3.11/site-packages
 COPY --from=build /usr/local/bin/uvicorn /usr/local/bin/uvicorn
 COPY --from=build /usr/local/bin/alembic /usr/local/bin/alembic
 COPY --from=build /app /app
 
 HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
-  CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:8000/docs')" || exit 1
+  CMD curl -f http://localhost:8000/api/health || exit 1
 
 EXPOSE 8000
 CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]