feat(docs): redesign portal with shared UI system

app/pages/packages/core.wrn

@@ -6,7 +6,7 @@ page wrnexuscore {
 
   view {
     <div class="docs-shell">
-      <a class="skip-link" href="#main">Skip to content</a>
+      <SkipLink label="Skip to content" href="#main" class="docs-skip-link" />
       <header class="topbar">
         <a class="brand" href="/"><span>W</span> WRNexusJS</a>
         <nav aria-label="Primary"><a href="/getting-started">Get started</a><a href="/packages">Packages</a><a href="/language">Language</a><a href="/architecture">Architecture</a></nav>
@@ -990,7 +990,8 @@ const registry = createRealtimeRegistry();
 bridgeRealtime(registry, createPubSub(redisDriver(process.env.REDIS_URL)));</code></pre></article></div></section></article>
       <aside class="on-this-page"><h2>On this page</h2><nav><a class="toc-level-2" href="#guide">Guide</a><a class="toc-level-3" href="#overview">Overview</a><a class="toc-level-3" href="#api">API</a><a class="toc-level-4" href="#context-middleware-wrnexus-core">Context &amp; middleware — @wrnexus/core</a><a class="toc-level-4" href="#authentication-wrnexus-core">Authentication — @wrnexus/core</a><a class="toc-level-4" href="#csrf-wrnexus-core">CSRF — @wrnexus/core</a><a class="toc-level-4" href="#rate-limiting-wrnexus-core">Rate limiting — @wrnexus/core</a><a class="toc-level-4" href="#request-logging-wrnexus-core">Request logging — @wrnexus/core</a><a class="toc-level-4" href="#caching-wrnexus-core">Caching — @wrnexus/core</a><a class="toc-level-4" href="#file-uploads-wrnexus-core">File uploads — @wrnexus/core</a><a class="toc-level-4" href="#streaming-sse-wrnexus-core">Streaming &amp; SSE — @wrnexus/core</a><a class="toc-level-4" href="#realtime-rooms-wrnexus-core">Realtime rooms — @wrnexus/core</a><a class="toc-level-4" href="#error-pages-wrnexus-core">Error pages — @wrnexus/core</a><a class="toc-level-4" href="#security-headers-cors-wrnexus-core">Security headers &amp; CORS — @wrnexus/core</a><a class="toc-level-4" href="#storage-cookies-sessions-localstorage-wrnexus-core">Storage: cookies, sessions, localStorage — @wrnexus/core</a><a class="toc-level-4" href="#low-level-security-helpers-wrnexus-core">Low-level security helpers — @wrnexus/core</a><a class="toc-level-4" href="#jsx-runtime-wrnexus-core-wrnexus-core-jsx-runtime-wrnexus-core-jsx-dev-runtime">JSX runtime — @wrnexus/core, @wrnexus/core/jsx-runtime, @wrnexus/core/jsx-dev-runtime</a><a class="toc-level-3" href="#usage">Usage</a><a class="toc-level-4" href="#a-minimal-middleware-chain">A minimal middleware chain</a><a class="toc-level-4" href="#password-auth">Password auth</a><a class="toc-level-4" href="#http-caching-with-etags">HTTP caching with ETags</a><a class="toc-level-4" href="#streaming-sse">Streaming SSE</a><a class="toc-level-4" href="#a-realtime-room">A realtime room</a><a class="toc-level-4" href="#jsx-rendering">JSX rendering</a><a class="toc-level-3" href="#requirements-notes">Requirements / Notes</a><a class="toc-level-2" href="#api">Complete API</a><a class="toc-level-2" href="#examples">Examples</a></nav></aside>
     </main>
-      <footer>WRNexusJS 0.2.64 · Private Developer Preview · Bun-native · Documentation generated from installed package APIs.</footer>
+      <footer><div class="footer-brand"><span class="footer-mark" aria-hidden="true">W</span><p><strong>WRNexusJS 0.2.64</strong><span>Complete API documentation generated from installed package declarations.</span></p></div><nav aria-label="Footer"><a href="/packages">All packages</a><a href="/getting-started">Get started</a><a href="/security">Security</a><a href="/support">Support</a><a href="/llms.txt">AI guide</a></nav><p class="footer-meta">Private Developer Preview · Bun-native</p></footer>
+      <BackToTop />
     </div>
   }
 }