feat(exo): example apps opt into editor preview via enablePreview [SPA-4692]

[Thomas Kellermeier (Chaoste)]

Stacked on #28. Demonstrates the minimum diff a customer applies to consume the new preview capabilities.

Summary

• Both the Next.js and SvelteKit examples call ExperienceRenderer — the hybrid renderer — directly from their server component / server load, and pass enablePreview on. No client-boundary shell needed; picking the right renderer at the import site is the whole customer-side change.
• Server render (via ServerExperienceRenderer internally) emits static first-paint HTML — SEO-friendly, no blank flash for slow devices.
• After hydration, ExperienceRenderer hands off to ClientExperienceRenderer, which owns the preview wire. Outside the Contentful editor the wire is a no-op — the SDK's ancestorOrigins check refuses to connect.

The three-renderer split, at the call site

// Marketing / blog / landing — pure SSR, no interactivity:
import { ServerExperienceRenderer } from '@contentful/experiences-react';

// Editable / preview-capable route — SSR + hydration + preview wire:
import { ExperienceRenderer } from '@contentful/experiences-react';

// Advanced client-only (tests, native shells):
import { ClientExperienceRenderer } from '@contentful/experiences-react';

Changes

• Next.js: app/[slug]/page.tsx + app/advanced/[slug]/page.tsx — swap ServerExperienceRenderer for ExperienceRenderer + enablePreview. That's the entire customer-side diff.
• SvelteKit: src/routes/[slug]/+page.svelte — same swap.

Bundle-size impact (next build)

• /[slug] route: 119 B (unchanged)
• First Load JS: 107 kB (unchanged)
• The renderer was already client-side via hydration; only the prop shape changed.