One command local dev with sample data #31

Why

A new contributor should see a working UI within minutes without a GitHub token or a testnet sync.

In this repo today

docker compose up already starts Postgres, the API and the web app (docker-compose.yml), but the database starts empty. Filling it needs sync, discover, scan and reconcile, which need network access and a token.

What to build

• A small anonymized sample dataset: 10 projects, 20 contracts and the full hourly series, as a SQL file under data/sample/.
• A one shot compose service that loads it when the projects table is empty.
• A script to regenerate the sample from a development database.
• docs/local-dev.md with the five commands a new contributor needs.

Acceptance criteria

• A fresh clone to a running UI in under 5 minutes on a laptop with Docker.
• The sample contains no data beyond public GitHub handles.

See CONTRIBUTING.md for conventions.