List contacts

curl 'https://api.sndr.sh/v1/contacts?status=subscribed&limit=20' \
  -H "Authorization: Bearer $SNDR_API_KEY"

{
  "data": [
    {
      "id":              "con_0e6b7f21-c58",
      "organization_id": "org_8d41c7a2-3f6",
      "email":           "jane@example.com",
      "first_name":      "Jane",
      "last_name":       "Doe",
      "attributes":      { "plan": "pro", "city": "Berlin" },
      "status":          "subscribed",
      "source":          "checkout",
      "created_at":      "2026-03-01T10:00:00Z",
      "updated_at":      "2026-03-01T10:00:00Z"
    }
  ],
  "has_more": false,
  "count":    1,
  "limit":    20,
  "counts":   { "subscribed": 1, "unsubscribed": 0, "bounced": 0, "complained": 0 }
}