feat: sync showcase with WRNexusJS 0.8.72 and @wrnexus/ui 0.8.88

- Sync app, public, scripts, test and examples from the framework's
  component-showcase: redesigned component demos, marketing blocks under
  /blocks, template and preview galleries, distinct Timeline/Section
  variants, Chat Bubble receipts, a top-placement Drawer demo, and the
  playground code panel fix (objects in array props no longer blank out).
- Standalone adaptations kept: the generator and tests read
  component-reference.json from the published @wrnexus/ui, and tests use
  the published @wrnexus/compiler and @wrnexus/syntax.
- Dependencies: every @wrnexus/* package to its latest release (ui 0.8.88,
  styles 0.8.26, core 0.8.16, cli 0.8.72, ...), happy-dom for the
  playground tests, Tailwind 4.3; bun.lock and package-lock.json refreshed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/layouts/gallery.wrn

@@ -0,0 +1,8 @@
+layout Gallery {
+ view {
+  <div class="gallery-shell">
+   <header class="gallery-header"><a href="/preview" class="showcase-brand">WRNexus UI</a><nav aria-label="Main navigation"><a href="/docs">Components</a><a href="/preview">Examples</a><a href="/block-library">Blocks</a><a href="/templates">Templates</a></nav></header>
+   <main class="gallery-main"><slot /></main>
+  </div>
+ }
+}