fix(brand-catalog): separate search input from content grid

- Add #brandCatalogSearch container in HTML for search inputs
- Move brand search input out of renderBrandList so it persists while typing
- Move parts search input out of renderPartsList so it persists while typing
- Reset now clears search container
- Bump JS cache bust to v=3

pos/templates/catalog.html

@@ -277,6 +277,7 @@
         <button onclick="BrandCatalog.hide()" class="btn btn--sm" style="background:none;border:1px solid var(--color-border);color:var(--color-text-primary);padding:8px 16px;border-radius:var(--radius-md);cursor:pointer;">&#10005; Cerrar</button>
       </div>
       <div id="brandCatalogBreadcrumb" style="margin-bottom:var(--space-3);color:var(--color-text-muted);font-size:var(--text-body-sm);"></div>
+      <div id="brandCatalogSearch" style="margin-bottom:var(--space-3);"></div>
       <div id="brandCatalogLoading" style="display:none;text-align:center;padding:var(--space-8);"><div class="spinner"></div></div>
       <div id="brandCatalogContent" style="display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:var(--space-3);"></div>
     </div>
@@ -294,6 +295,6 @@
   <script src="/pos/static/js/onboarding.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
   <script src="/pos/static/js/pwa-install.js" defer></script>
-  <script src="/pos/static/js/brand-catalog.js?v=2" defer></script>
+  <script src="/pos/static/js/brand-catalog.js?v=3" defer></script>
 </body>
 </html>