Bulk Dmarc Reports

2-20 reports, bounded at the model so an oversize body is a 422 at parse.

The batch. reports_parsed is what the settle gate reads.

combined is one entry per reported domain (a report naming none is grouped under domain: null), computed over the pooled rows of every parsed report for it — a report sent twice (same reporter + report id) is pooled once, as intake's duplicate rule — org_name/report_id are null, the dates are the batch's min/max.