feat(mobile-expo): SectionDispatcher scaffold and shared renderer types

[Ur-imazing]

Background

The Expo watch app renders server-driven UI by mapping each CMS section type to a React Native component. Before individual renderers can be built, the app needs a dispatcher that switches on __typename and shared types/props interfaces that all renderers conform to.

This is the foundation sub-issue of #93. Every subsequent renderer sub-issue plugs a real component into the dispatcher in place of a placeholder stub.

Expected outcome

• A SectionDispatcher component that receives a section object (with __typename) and renders the matching renderer.
• Placeholder/stub components for all 10 section types so the dispatcher compiles and renders fallback UI for unimplemented types.
• Shared TypeScript types/interfaces for section props, aligned with the data layer models from feat(mobile-expo): expand data layer for all 10 CMS section types #304.
• File structure under mobile/expo/.../sections/ with one file per renderer (stubs) and the dispatcher.

Acceptance criteria

• SectionDispatcher component switches on __typename and renders the correct component.
• Placeholder stubs exist for all 10 types: VideoHero, MediaCollection, CTA, Text, Video, BibleQuotesCarousel, RelatedQuestions, Card, Section, Container.
• Stubs render a visible fallback (e.g. type name label) so missing renderers are obvious during development.
• Shared props interfaces exported for each section type.
• Dispatcher handles unknown __typename gracefully (e.g. logs warning, renders nothing).
• File structure: mobile/expo/.../sections/{SectionDispatcher, VideoHero, MediaCollection, ...}.

Possible solution(s)

1. Simple switch/map object in SectionDispatcher: { ComponentSectionsVideoHero: VideoHeroRenderer, ... }.
2. Each stub exports a component matching the shared interface; real implementations replace stubs in subsequent issues.

References

• Parent: feat(mobile-expo): section renderers for all 10 CMS section types #93 (tracking issue for all section renderers)
• Depends on: feat(mobile-expo): expand data layer for all 10 CMS section types #304 (expanded data layer — provides typed section models)
• apps/cms/schema.graphql — ExperienceSectionsDynamicZone union (line 693)