docs(example-iot-telemetry): write comprehensive step-by-step tutorial, Containerfile and compose stack

[crapougnax]

Part of parent story #41.

🎯 Goal

Author the comprehensive advanced-level tutorial and deployable container stack for the IoT Telemetry reference application.

📋 Specification

1. Create examples/iot-telemetry-engine/docker-compose.yml:
   • Services: PostgreSQL, RabbitMQ management, MinIO S3, Telemetry Worker.
2. Create examples/iot-telemetry-engine/Containerfile:
   • Multi-arch OCI build (linux/amd64, linux/arm64) adhering to Quatrain OCI label standards.
3. Create examples/iot-telemetry-engine/README.md detailing:
   • Architecture diagram: Webhooks ➔ RabbitMQ ➔ Workers ➔ PostgreSQL/S3 ➔ Gemini AI.
   • Step 1: Modeling devices with MDM capabilities.
   • Step 2: Ingesting sensor frames with RabbitMQ concurrent workers.
   • Step 3: Polyglot ObjectUri persistence across PostgreSQL, AMQP, and S3.
   • Step 4: AI Anomaly diagnosis with Google Gemini schema guarantee.
   • Step 5: Sovereign deployment on Bare-metal or Kubernetes via Podman / Docker.
4. Cross-link tutorial in docs under docs/pages/tutorials/iot-telemetry-pipeline.md.