fix(config): prevent card text overflow; fix(onboarding): persist completion server-side

Cards/Grid:
- Add min-width:0 to .device-grid to prevent grid overflow
- Add max-width:100%, overflow:hidden, word-break:break-word to .device-card
- Add min-width:0 and overflow-wrap to .device-card__body
- Bump config.css cache-bust to v=2

Onboarding:
- Add GET/POST /pos/api/config/onboarding-status endpoints in config_bp.py
- onboarding.js now checks server first before showing wizard
- On finish, POSTs completion to server (tenant_config table)
- Falls back to localStorage for fast path and offline resilience
- Bump onboarding.js cache-bust to v=2 in catalog.html

pos/templates/catalog.html

@@ -276,10 +276,10 @@
         <h2 style="margin:0;font-family:var(--font-heading);font-size:var(--text-h3);">Catalogo por Marca</h2>
         <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="brandCatalogBreadcrumb" style="margin-bottom:var(--space-3);"></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 id="brandCatalogLoading" class="loading"><div class="spinner"></div></div>
+      <div id="brandCatalogContent"></div>
     </div>
   </div>
 
@@ -292,7 +292,7 @@
   <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>
-  <script src="/pos/static/js/onboarding.js" defer></script>
+  <script src="/pos/static/js/onboarding.js?v=2" defer></script>
   <script>
     if('serviceWorker' in navigator){
       navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'}).then(function(reg){
@@ -308,6 +308,6 @@
     }
   </script>
   <script src="/pos/static/js/pwa-install.js" defer></script>
-  <script src="/pos/static/js/brand-catalog.js?v=4" defer></script>
+  <script src="/pos/static/js/brand-catalog.js?v=9" defer></script>
 </body>
 </html>