Observability: Local development stack

[i5okie]

Description

Add the grafana/otel-lgtm observability stack to the local docker-compose environment so developers can validate instrumentation locally before deploying.

Context

No devcontainer. The compose file is demo/docker-compose.yml — webvh-server runs as a compose service on webvh-network, so http://lgtm:4318 is the correct endpoint.

Requirements

• Add grafana/otel-lgtm service to demo/docker-compose.yml on the webvh-network (ports 3000:3000, 4317:4317, 4318:4318)
• Add to the webvh-server service environment:
  • OTEL_EXPORTER_OTLP_ENDPOINT=http://lgtm:4318
  • OTEL_SERVICE_NAME=didwebvh-server-py
  • OTEL_EXPORTER_OTLP_PROTOCOL=http/protobuf
  • OTEL_TRACES_EXPORTER=otlp
  • OTEL_METRICS_EXPORTER=otlp
  • OTEL_PYTHON_LOG_CORRELATION=true
• Update README or CONTRIBUTING with local observability instructions

Acceptance Criteria

• docker compose -f demo/docker-compose.yml up starts the LGTM stack alongside the service
• Grafana accessible at http://localhost:3000
• Traces visible in Tempo after instrumentation is added and test requests are made locally
• Developer docs updated