feat: CSR-176 Render custom_elements' json-render output format (optional).

[drubot]

Frontend half of CSR-176 / upstream custom_elements #3580092 (MR !189): render the json-render output format — a flat element map {root, elements: {key: {type, props, children, slots}}} — on the decoupled frontend.

What this does

• Opt-in module option jsonRender (default false): registers the global DrupalCeJsonRender component. The component statically imports @json-render/vue, so nothing lands in the bundle unless enabled.
• Optional dependencies: @json-render/vue (+ its zod peer) declared as optional peerDependencies — install with npm i @json-render/vue zod only when using the format.
• Detection in renderCustomElements: a content object with root + elements routes to the json-render renderer; with the option disabled, a clear console error explains what to enable/install (no accidental fallback into the custom-element default-component resolution).
• Same component resolution as the other formats: every spec type resolves via resolveCustomElement, so existing app components serve all three formats.
• Slot bridging: @json-render/vue's renderer only walks children; the named slots maps custom_elements emits are bridged by rendering each slot entry as a sub-spec rooted at that element, wired into the Vue component's named slots.
• drupal-markup mapping: spec elements of type drupal-markup carry inline HTML in props.markup (per MR !189's normalizer) and render through the app's drupal-markup component (content prop).
• Rendering runs inside JSONUIProvider, so json-render's state/visibility/action contexts are available with defaults.

Testing

• New test/nuxt/drupalCeJsonRender.test.ts: spec detection, full render of the MR's example shape (props, children, named slot, drupal-markup), and the renderCustomElements routing path. Full suite 160/160 green, changed files eslint-clean.
• Backend regression run of the upstream MR against LDP: ldp-project #3075.

🤖 Generated with Claude Code

[fago]

we should not have to guess here. when the setting is on, use it.

[fago]

does not make sense as component really. this is the wrong tool

[wotnak]

Support for named slots in @json-render/vue was recently merged. vercel-labs/json-render@a4d033c
It isn't yet included in tagged release, but hopefully will be soon, then the custom handling of named slots will be no longer necessary.