Observability: Local development stack

## Description

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

## Context

Both `tenant-ui` and `traction-agent` run as compose services in `scripts/docker-compose.yml` on a shared network, so `http://lgtm:4318` is the correct endpoint for both. The `traction_innkeeper` plugin runs inside the ACA-Py process — no separate container.

## Requirements

- Add `grafana/otel-lgtm` service to `scripts/docker-compose.yml` on the same network (ports `3000:3000`, `4317:4317`, `4318:4318`)
- Add to the `tenant-ui` service environment:
- `OTEL_EXPORTER_OTLP_ENDPOINT=http://lgtm:4318`
- `OTEL_SERVICE_NAME=traction-tenant-ui`
- `OTEL_EXPORTER_OTLP_PROTOCOL=http/protobuf`
- `OTEL_TRACES_EXPORTER=otlp`
- `OTEL_METRICS_EXPORTER=otlp`
- Add to the `traction-agent` service environment:
- `OTEL_EXPORTER_OTLP_ENDPOINT=http://lgtm:4318`
- `OTEL_SERVICE_NAME=traction-agent`
- `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 scripts/docker-compose.yml up` starts the LGTM stack alongside both components
- [ ] Grafana accessible at `http://localhost:3000`
- [ ] Traces from both tenant-ui and the ACA-Py agent visible in Tempo after instrumentation is added
- [ ] Developer docs updated

Start with scripts/docker-compose.yml and inspect the tenant-ui and traction-agent services and their shared network. Run docker compose -f scripts/docker-compose.yml up, verify Grafana at http://localhost:3000 and the LGTM service endpoints, then update README or CONTRIBUTING with the local observability instructions. Done means the stack starts alongside both components and the required environment settings and documentation are present.

Written by the indexing model from the issue text.