🔇 fix: Hide Button Icons from Screen Readers (#10776)

If you've got a screen reader that is reading out the whole page,
each icon button (i.e., `<button><SVG></button>`) will have both
the button's aria-label read out as well as the title from the
SVG (which is usually just "image").

Since we are pretty good about setting aria-labels, we should instead
use `aria-hidden="true"` on these images, since they are not useful
to be read out.

I don't consider this a comprehensive review of all icons in the app,
but I knocked out all the low hanging fruit in this commit.

client/src/components/Chat/Messages/Content/AgentHandoff.tsx

@@ -74,6 +74,7 @@ const AgentHandoff: React.FC<AgentHandoffProps> = ({ name, args: _args = '' }) =
         {hasInfo && (
           <ChevronDown
             className={cn('ml-1 h-3 w-3 transition-transform', showInfo && 'rotate-180')}
+            aria-hidden="true"
           />
         )}
       </div>