Submit bulk domain analysis (results emailed)

Submit a large domain list for asynchronous analysis with email delivery.

Unlike /analyze/batch (<=50 domains, processed in-request), a bulk upload only persists a BulkJob row and dispatches a worker task: the per-domain gate -> dispatch -> settle sequence runs in process_bulk_job with the same post-dispatch billing settlement as the batch pass 3, and when every child job is terminal the hygiene tick flips the row to exporting so the export task renders CSV/JSON, uploads to S3, and emails presigned links to the account address. Invalid domains are recorded as per-item errors on the bulk job (batch precedent), not a whole-request 422.