SDC strict null validation breaks optional props

Problem/Motivation

Drupal 11's ComponentValidator rejects null for bare types (type: string, type: array). Prototype component schemas use bare types for optional props, so leaving any optional field empty causes InvalidComponentException: NULL value found, but a string is required and breaks page rendering.

The default Splide config in slideshow.twig uses the bare word loop as a value 'type': loop. Outside a {% for %} block, loop is undefined in Twig and evaluates to null, producing data-splide='{"type":null}'. Splide fails to initialize and the carousel does not function.

Steps to reproduce

1. Create a paragraph of type CTA, Pullquote, Slideshow, Teaser, or Video.
2. Leave at least one optional field (title, caption, link, etc.) blank.
3. View the node — the page throws an `InvalidComponentException`.

Create a slideshow
1. Add a Slideshow paragraph with at least one slide.
2. Do not pass an explicit options.type from the bridge template.
3. Inspect the rendered HTML — data-splide contains "type":null and the carousel is broken.

Proposed resolution

• converts bare types to type: ['string', 'null'] and removes required arrays from optional props.
• change 'type': loop to 'type': 'loop' for slideshow