fix(desktop): perf tweaks

packages/ui/src/components/basic-tool.css

@@ -1,4 +1,5 @@
 [data-component="tool-trigger"] {
+  content-visibility: auto;
   width: 100%;
   display: flex;
   align-items: center;

packages/ui/src/components/message-part.css

@@ -1,4 +1,5 @@
 [data-component="assistant-message"] {
+  content-visibility: auto;
   width: 100%;
   display: flex;
   flex-direction: column;