{
  "type": "text",
  "key": "avatar_custom_url",
  "constant": "AVATAR_CUSTOM_URL",
  "description": "Custom avatar URL template (only used when avatar provider is custom). Placeholders: {email}, {username}, {name}, {hash}, {app_url}",
  "required": false,
  "placeholder": "https://example.com/avatar/{hash}",
  "validation": "nullable|string|max:2048",
  "options": [],
  "category": "security",
  "sensitive": false
}