feat: New UI design, update thread, thread-list, and css (#3)

Matches new template design in assistant-cloud-starter

Author: AVGVSTVS96

app/globals.css

@@ -116,7 +116,43 @@
   * {
     @apply border-border outline-ring/50;
   }
+
+  :root {
+    color-scheme: light;
+  }
+
+  :root.dark {
+    color-scheme: dark;
+  }
+
   body {
     @apply bg-background text-foreground;
   }
+  
+  /* Scrollbar styling */
+  ::-webkit-scrollbar {
+    width: 12px;
+  }
+
+  ::-webkit-scrollbar-thumb {
+    @apply bg-muted-foreground/20;
+    border-radius: 6px;
+    border: 2px solid transparent;
+    background-clip: padding-box;
+  }
+
+  ::-webkit-scrollbar-thumb:hover {
+    @apply bg-muted-foreground/30;
+  }
+
+  /* Firefox only scrollbar styling */
+  @-moz-document url-prefix() {
+    * {
+      scrollbar-color: oklch(0.552 0.016 285.938 / 25%) transparent;
+    }
+
+    .dark * {
+      scrollbar-color: oklch(0.705 0.015 286.067 / 25%) transparent;
+    }
+  }
 }