List suppressions

curl 'https://api.sndr.sh/v1/suppressions' \
  -H "Authorization: Bearer $SNDR_API_KEY"

{
  "data": [
    {
      "organization_id": "org_8d41c7a2-3f6",
      "address":         "hard-bounce@example.com",
      "reason":          "bounce",
      "detail":          "550 5.1.1 user unknown",
      "created_at":      "2026-05-15T10:30:00Z"
    },
    {
      "organization_id": "org_8d41c7a2-3f6",
      "address":         "optout@example.com",
      "reason":          "manual",
      "created_at":      "2026-05-10T08:00:00Z"
    }
  ]
}