feat: Passwordless cross-device authentication

- Arkitektur: docs/auth/passwordless-architecture.md
- Backend: iom/quixzoom-auth-service/ (FastAPI + Redis)
- Webb: quixzoom-market-pages/se/login/ (QR-kod + polling)
- App: iom/quixzoom-app/src/features/auth/ (push + deep links)

Flöde: QR-kod → app-godkännande → webb-inloggad

quixzoom-landing-fixed/images.html

@@ -129,7 +129,7 @@
     .logo span { color: #0071e3; }
     .nav-cta {
       background: #0071e3; color: #fff;
-      padding: 8px 18px; border-radius: 20px;
+      padding: 8px 18px; border-radius: var(--radius-xl);
       font-size: 14px; font-weight: 600;
       text-decoration: none;
     }
@@ -166,7 +166,7 @@
       gap: 24px;
     }
     .card {
-      border-radius: 16px;
+      border-radius: var(--radius-lg);
       overflow: hidden;
       background: #fff;
       box-shadow: 0 2px 12px rgba(0,0,0,0.08);
@@ -201,7 +201,7 @@
       font-size: 11px;
       font-weight: 600;
       padding: 3px 10px;
-      border-radius: 20px;
+      border-radius: var(--radius-xl);
       margin-top: 10px;
     }
 
@@ -213,7 +213,7 @@
     }
     .featured img {
       width: 100%;
-      border-radius: 20px;
+      border-radius: var(--radius-xl);
       box-shadow: 0 4px 24px rgba(0,0,0,0.10);
     }
 
@@ -239,7 +239,7 @@
     }
     .alt-names span {
       background: #fff; border: 1px solid #d2d2d7;
-      border-radius: 20px; padding: 5px 14px;
+      border-radius: var(--radius-xl); padding: 5px 14px;
       font-size: 13px; color: #3a3a3c;
     }