QA fixes: real listing creation, profile save, favorites, missing pages

- SellItemPage: real file upload + API listing creation + activate
- CreateProfilePage: save profile via PUT /users/profile
- ProductDetailPage: wire edit/delete/message buttons, show edit for owner
- ListingCard: persist favorites via API, show real images
- Footer: connect newsletter subscribe to API
- Router: add /dashboard/listings and /dashboard/saved routes
- Backend: add GET /listings/favorites endpoint
- New pages: MyListingsPage, SavedItemsPage
- Fix unused imports causing build failures

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

client/src/router.tsx

@@ -14,6 +14,8 @@ import { MyOffersPage } from './pages/MyOffersPage';
 import { NotificationsPage } from './pages/NotificationsPage';
 import { SoldItemsPage } from './pages/SoldItemsPage';
 import { SettingsPage } from './pages/SettingsPage';
+import { MyListingsPage } from './pages/MyListingsPage';
+import { SavedItemsPage } from './pages/SavedItemsPage';
 
 export const router = createBrowserRouter([
   {
@@ -36,6 +38,8 @@ export const router = createBrowserRouter([
           { path: 'notifications', element: <NotificationsPage /> },
           { path: 'sold', element: <SoldItemsPage /> },
           { path: 'settings', element: <SettingsPage /> },
+          { path: 'listings', element: <MyListingsPage /> },
+          { path: 'saved', element: <SavedItemsPage /> },
         ],
       },
     ],