fix(web): fill the provider row card

Raises a configured provider's row onto layer 3 so it reads as a surface
rather than an outline. No-op under the light theme, where layer 3 and the
panel are both white.

packages/client/ui-models/src/client/ModelsSection.module.css

@@ -56,6 +56,7 @@
   display: flex;
   flex-direction: column;
   gap: 12px;
+  background: var(--dsw-alias-bg-layer-3);
 }
 
 .rowHead {