curl --request POST \
  --url https://api.coval.dev/v1/tags \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '
{
  "tag_name": "production"
}
'

{
  "tag": {
    "name": "tags/01HX2ABC3DEF4GHI5JKL6MNO7P",
    "id": "01HX2ABC3DEF4GHI5JKL6MNO7P",
    "tag_name": "production",
    "color": "#3b82f6",
    "create_time": "2025-10-14T12:00:00Z",
    "created_by": "engineer@example.com"
  }
}