fix(web): add /listings to middleware publicPaths (TEC-3090)

Unauthenticated requests to /listings were being 302-redirected to /login
because '/listings' was missing from the publicPaths allowlist. /listings
is the public marketplace board and must be accessible without auth.

Unblocks 5 Playwright DataTable specs + smoke test (TEC-3040).

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/middleware.ts

@@ -4,7 +4,7 @@ import { routing } from '@/i18n/routing';
 
 const intlMiddleware = createIntlMiddleware(routing);
 
-const publicPaths = ['/login', '/register', '/search', '/auth/callback'];
+const publicPaths = ['/login', '/register', '/search', '/listings', '/auth/callback'];
 const publicExactPaths = ['/'];
 const authOnlyPaths = ['/login', '/register'];