(VDB-68) Verify log block hash matches header block hash

- Delete header on conflict to prompt data refresh (cascade deletes all
  data associated with that block)
- Derive header hash from rpc payload rather than computing it from data
  (prevents hash mismatch between blockchain and cache)

pkg/transformers/vat_init/repository.go

@@ -39,6 +39,12 @@ func (repository VatInitRepository) Create(headerID int64, models []interface{})
 			return fmt.Errorf("model of type %T, not %T", model, VatInitModel{})
 		}
 
+		err = shared.ValidateHeaderConsistency(headerID, vatInit.Raw, repository.db)
+		if err != nil {
+			tx.Rollback()
+			return err
+		}
+
 		_, err = tx.Exec(
 			`INSERT INTO maker.vat_init (header_id, ilk, log_idx, tx_idx, raw_log)
 			VALUES($1, $2, $3, $4, $5)`,