Screenshot/file URLs written to a run's binaryOutput were built from the
internal MinIO host/port (defaulting to localhost:9000). Any deployment
where MinIO sits behind a reverse proxy or on a non-localhost public
address produced unreachable URLs, so stored screenshots never loaded.
Prefer a complete public base URL via MINIO_PUBLIC_URL (e.g.
https://storage.example.com) and fall back to the existing
MINIO_PUBLIC_HOST:MINIO_PORT composition for local/dev setups, so existing
configurations are byte-for-byte unchanged. Documents the variable in ENVEXAMPLE.
Fixes#832
Maheswari Bajji