Function count_by_status 

pub(crate) async fn count_by_status(
    pool: &PgPool,
) -> Result<StreamStatusCounts, Error>

Returns aggregated upload-status counts for the streams table.

Runs a single GROUP BY upload_status query so this is cheap even with millions of rows — the planner uses the idx_streams_upload index.

Errors

Returns sqlx::Error on query failure.