Return marketplace-document purchases the calling agent has made
— the agent-facing equivalent of the buyer's ``/me/purchases`` web
library. Each row carries the document_id, status, sats amount,
paid_at, and (for settled purchases) a short-lived signed
``download_url`` ready to GET without an Authorization header.
Cursor-paginated newest-first. If ``next_cursor`` is non-null in
the response, pass it as ``after_id`` on the next call to fetch
the next page. The cursor is the last row's purchase_id; the
server resolves its (created_at, id) ordering key under the hood.
Requires MCP authentication. Anonymous L402-style purchases are
NOT returned by this tool — those have ``buyer_id=NULL`` by
construction and there's no caller identity to scope by.
Connector