feat(cms): add or align schema for CTA component

[Kneesal]

Background

CTA (call-to-action) blocks need a clear schema so editors can configure buttons/links and optional copy. An existing sections/cta.json may need to be formalized or extended.

Expected outcome

• CTA component has a defined schema: at least label, link (or URL), optional heading/description, and any variant (e.g. primary/secondary) for the web app.

Acceptance criteria

• CTA component schema is defined or updated in CMS (e.g. apps/cms/src/components/sections/cta.json).
• Attributes cover label, link/URL, optional heading/description and variant.
• Component registered and available; GraphQL regenerated if contracts change.

Possible solution(s)

1. Review sections/cta.json; add missing fields (e.g. variant, description) and ensure link structure matches web.
2. If CTA is used inside other components, ensure it is registered as a nested component where needed.

References

• apps/cms/src/components/sections/cta.json

• apps/cms/schema.graphql

• Parent: epic(cms): Experience schema for Easter-style watch page #175 Epic A (CMS)

• Related (web implementation): feat(web): add or align CTA component #158