Returns a paginated list of campaigns scoped to the authenticated account, newest first by default. Each item carries eds_uuid/footer_uuid (the campaign's default sending domain and footer) and num_sequences (count of non-deleted sequences). This is the entry point of the campaign flow: list campaigns here, then fetch one with get_campaign, drill into a sequence with get_sequence, or create a new campaign with create_campaign. Pagination is offset-based via limit/offset; total is the full count before paging.