add order status lookup for customers

Magic link flow on contact page: customer enters email, gets a
time-limited signed link, clicks through to /orders showing all their
paid orders and full detail pages with thumbnails and product links.

- OrderLookupController generates/verifies Phoenix.Token signed links
- Contact LiveView handles lookup_orders + reset_tracking events
- Orders and OrderDetail LiveViews gated by session email
- Order detail shows thumbnails, links to products still available
- .themed-button gets base padding/font-weight so all usages are consistent
- order-summary-card sticky scoped to .cart-grid (was leaking to orders list)
- 27 new tests (1095 total)

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

assets/css/theme-layer2-attributes.css

@@ -281,6 +281,8 @@
     border-radius: var(--t-radius-button);
     border: none;
     cursor: pointer;
+    padding: 0.75rem 1.5rem;
+    font-weight: 600;
   }
 
   & .themed-button-outline {
@@ -289,6 +291,8 @@
     border: 1px solid var(--t-border-default);
     border-radius: var(--t-radius-button);
     cursor: pointer;
+    padding: 0.75rem 1.5rem;
+    font-weight: 600;
   }
 
   & .themed-card {