fix(w48): move entity-rag demo to docs/demo/ for GitHub Pages

GitHub Pages serves from /docs — demo was unreachable at demo/.
Fixed WASM import path (../pkg/edgevec.js) and hub back-link (../hub.html).
Verified working locally: WASM loads, 1000 vectors indexed, search functional.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: matte1782

demo/entity-rag/data.json docs/demo/entity-rag/data.jsondemo/entity-rag/data.json renamed to docs/demo/entity-rag/data.json

@@ -795,7 +795,7 @@
         <span class="header__version">v0.9.0</span>
       </div>
       <nav class="header__nav">
-        <a href="../../docs/demo/hub.html" class="header__link">&larr; DEMO HUB</a>
+        <a href="../hub.html" class="header__link">&larr; DEMO HUB</a>
         <a href="https://github.com/matte1782/edgevec" class="header__link" target="_blank" rel="noopener">GITHUB</a>
       </nav>
     </div>
@@ -1456,7 +1456,7 @@ <h1 class="hero__title glitch neon-pulse" data-text="ENTITY_RAG_INTERFACE">ENTIT
         $wasmStatus.textContent = 'LOADING...';
         $wasmStatus.className = 'status-bar__value status-bar__value--loading';
 
-        const wasm = await import('../../pkg/edgevec.js');
+        const wasm = await import('../pkg/edgevec.js');
         await wasm.default();
 
         $wasmStatus.textContent = 'READY';