test: add docker-compose with mosquitto and python subscriber

test/README.md

@@ -0,0 +1,23 @@
+# Test compose
+
+This folder contains a simple Docker Compose stack to run the Go server together with an MQTT broker and a Python subscriber client.
+
+Quickstart:
+
+```bash
+cd test
+docker compose up --build
+```
+
+- The Go server is built from the repository `Dockerfile` and is configured via environment variables in `docker-compose.yml`.
+- The MQTT broker is `eclipse-mosquitto` and is exposed on port `1883`.
+- The `subscriber` service runs `subscribe.py` and prints any messages published to the `lambdaiot` topic.
+
+To run the Python subscriber locally instead of in Docker:
+
+```bash
+python3 -m venv .venv
+source .venv/bin/activate
+pip install -r requirements.txt
+MQTT_BROKER=localhost:1883 MQTT_TOPIC=lambdaiot python subscribe.py
+```