release: v1.0.0

[jamofer]

Summary

• Bump backend / frontend / testjam-client to 1.0.0.
• docker-compose.yml now pulls ghcr.io/jamofer/testjam-{api,web}:${TESTJAM_VERSION:-v1.0.0} instead of building from source. Self-hosters download two files (compose + env) and docker compose up.
• .env.example documents TESTJAM_VERSION with the explicit warning to avoid latest in production.
• getting-started.{md,es.md} updated: clone step replaced by a two-file curl install + upgrade flow (bump tag → compose pull → up -d).

After merge

git checkout master && git pull
git tag v1.0.0
git push origin v1.0.0

The publish-images workflow fires on v* and pushes ghcr.io/jamofer/testjam-api:v1.0.0 + :latest and the same for testjam-web, with GIT_REF / GIT_COMMIT / BUILD_DATE baked in so /about surfaces the release values. After the workflow finishes, mark both GHCR packages public (Settings → Packages → visibility) so the curl install works for anonymous users.