/// Uniquely identifies a resource kind within the API server.
///
/// `ResourceKey` combines the three components of a kapi resource identifier:
/// `group`, `version`, and `kind`. It is used as a lookup key for schema
/// validation, event bus routing, and store operations.
///
/// # Example
///
/// ```
/// use kapi_core::ResourceKey;
///
/// let key = ResourceKey {
/// group: "example.io".to_string(),
/// version: "v1".to_string(),
/// kind: "Widget".to_string(),
/// };
/// ```