fix(catalog): descarga de plantilla de precios proveedor con token

El enlace <a> a /pos/api/supplier-catalog/prices/template fallaba con 401
porque la navegación normal no envía el header Authorization. Se reemplaza
por un botón que descarga el blob vía fetch con Bearer token y dispara la
descarga del cliente. También se corrige clase btn-primary -> btn--primary.

pos/static/js/catalog.js

@@ -2148,6 +2148,31 @@
         }
     }
 
+    async function downloadPriceTemplate() {
+        try {
+            var res = await fetch('/pos/api/supplier-catalog/prices/template', {
+                headers: { 'Authorization': 'Bearer ' + token }
+            });
+            if (!res.ok) {
+                var data = await res.json().catch(function() { return {}; });
+                if (uploadPricesStatus) uploadPricesStatus.innerHTML = '<span style="color:var(--color-error);">' + esc(data.error || 'Error al descargar plantilla') + '</span>';
+                return;
+            }
+            var blob = await res.blob();
+            var url = URL.createObjectURL(blob);
+            var a = document.createElement('a');
+            a.href = url;
+            a.download = 'supplier_prices_template.csv';
+            document.body.appendChild(a);
+            a.click();
+            a.remove();
+            URL.revokeObjectURL(url);
+            if (uploadPricesStatus) uploadPricesStatus.innerHTML = '<span style="color:var(--color-success);">✓ Plantilla descargada.</span>';
+        } catch (e) {
+            if (uploadPricesStatus) uploadPricesStatus.innerHTML = '<span style="color:var(--color-error);">Error de red: ' + esc(e.message) + '</span>';
+        }
+    }
+
     function shouldShowUploadPricesButton() {
         try {
             var user = JSON.parse(localStorage.getItem('pos_employee') || '{}');
@@ -2180,6 +2205,7 @@
         openUploadPricesModal: openUploadPricesModal,
         closeUploadPricesModal: closeUploadPricesModal,
         submitUploadPrices: submitUploadPrices,
+        downloadPriceTemplate: downloadPriceTemplate,
     };
 
     // ─── INIT ───

pos/templates/catalog.html

@@ -294,8 +294,8 @@
         <input type="file" id="uploadPricesFile" accept=".csv,.xlsx,.xls" style="width:100%;" />
       </div>
       <div style="display:flex;gap:var(--space-2);justify-content:flex-end;">
-        <a href="/pos/api/supplier-catalog/prices/template" class="btn btn--ghost" style="text-decoration:none;">Descargar plantilla</a>
+        <button class="btn btn--ghost" onclick="CatalogApp.downloadPriceTemplate()">Descargar plantilla</button>
-        <button class="btn btn-primary" onclick="CatalogApp.submitUploadPrices()">Subir precios</button>
+        <button class="btn btn--primary" onclick="CatalogApp.submitUploadPrices()">Subir precios</button>
       </div>
       <div id="uploadPricesStatus" style="margin-top:var(--space-3);font-size:var(--text-body-sm);"></div>
     </div>
@@ -321,7 +321,7 @@
   <script src="/pos/static/js/splash-loader.js?v=1" defer></script>
   <script src="/pos/static/js/pos-utils.js?v=2" defer></script>
   <script src="/pos/static/js/sidebar.js" defer></script>
-  <script src="/pos/static/js/catalog.js?v=6" defer></script>
+  <script src="/pos/static/js/catalog.js?v=7" defer></script>
   <script src="/pos/static/js/offline-banner.js" defer></script>
   <script src="/pos/static/js/chat.js" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>