curl -X GET https://api.thinnest.ai/knowledge/list \
  -H "Authorization: Bearer $THINNESTAI_API_KEY"

{
  "sources": [
    {
      "id": 1,
      "name": "Product FAQ",
      "type": "text",
      "status": "ready",
      "char_count": 4500,
      "chunk_count": 12,
      "created_at": "2026-03-01T10:00:00Z"
    },
    {
      "id": 2,
      "name": "https://docs.example.com",
      "type": "url",
      "status": "processing",
      "char_count": null,
      "chunk_count": null,
      "created_at": "2026-03-07T14:00:00Z"
    },
    {
      "id": 3,
      "name": "manual.pdf",
      "type": "file",
      "status": "ready",
      "char_count": 28000,
      "chunk_count": 85,
      "created_at": "2026-03-05T09:00:00Z"
    }
  ]
}