class CreateLayer

A Layer is a type of `Content` that composites either a single `Image` or a solid

color. It separates visual properties (such as size, flip, opacity, and blending)

from the raw pixel data.

Unlike typical `Content` items which represent a static visual resource, a Layer is designed

to be a dynamic container for an image sequence. Typical usage involves setting the layer's

visual properties and image metadata infrequently, and then rapidly swapping the active

`Image` (e.g. on every frame) with another image of matching metadata.

This separation allows a single `Image` resource to be reused across multiple layers with

different visual configurations simultaneously.

To use a Layer:

1. Create a `Layer` using [`CreateLayer`].

2. Set properties on the `Layer` via [`SetLayerProperties`], including the

composition mode.

3. For an image layer, associate an `Image` with the `Layer` via [`SetLayerImage`].

4. Add the `Layer` to a `LayerStack` via [`SetStackLayers`].

5. Set the `LayerStack` as the content of a node via [`SetTransformContent`].

`layer_id` must satisfy the identifier rules documented on [`LayerId`].