Get product activity

First page of every activity source a product has: one entry per conversational surface (messaging conversations or client-conversation records) and one per distinct agent capability. Agent rows are RunListRows read the way GET /v1/runs?agentId= reads them, so a client continues that source with /v1/runs and the surface sources with their own list endpoints; rows, cursors and hasMore match. A source that fails returns empty rows plus an error; the response is still 200.