feat: media-image rich-editor extension

[bambamboole]

Summary

Adds a media-image rich-editor extension built on lattice's server-side extension API: pick images from the media library inside RichEditor, store only {id, alt, conversion} per node, and resolve URLs server-side on every render/prefill (temporary/signed disk URLs just work).

• PHP: MediaImage (#[AsEditorExtension('media-image')], registered app-wide) + MediaImageNode (tiptap-php). prepareDocument() batch-resolves ids into ephemeral url/width/height/mediaAlt attrs that are scrubbed before storage; validateDocument() rejects missing, gate-denied, and non-image media with per-id messages; the sanitizer allows exactly what renderHTML() emits.
• Client: Tiptap node with React NodeView (image preview, missing-media placeholder, alt override + conversion size controls) and a toolbar button that opens the existing LibraryView dialog (carried in the extension's wire props). The dialog is lazy-loaded so the media grid stays out of the eager bundle.
• Model linking: MediaImage::idsIn($document) feeds the existing syncMedia() — documented in the README together with the mediaConversions() pairing.
• Deps: requires lattice ≥0.36 — 0.36.0 ships the rich-editor fix that runs validation/casting for array-shaped document submissions, which this extension's attach gate relies on.

Usage:

RichEditor::make('body')->withExtensions(MediaImage::make()->conversions('hero'));

$post->update(['body' => $validated['body']]);
$post->syncMedia(MediaImage::idsIn($validated['body']), 'content');

Testing

• composer check green on lattice 0.36.0: Pint, Larastan, 143 Feature tests (409 assertions) — extension seams (wire shape, ephemeral scrub, batch URL resolution incl. conversions + nested nodes, sanitizer attrs, validation modes, idsIn).
• npm run test (39) + npm run typecheck + npm run build green.
• Browser suite 9/9 green, including a full round trip: insert via toolbar → save → stored doc has ids only (no url), attachment row in the content collection → reload re-renders the image.

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