🔇 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/AddMultiConvo.tsx

@@ -43,7 +43,7 @@ function AddMultiConvo() {
       data-testid="parameters-button"
       className="inline-flex size-10 flex-shrink-0 items-center justify-center rounded-xl border border-border-light bg-transparent text-text-primary transition-all ease-in-out hover:bg-surface-tertiary disabled:pointer-events-none disabled:opacity-50 radix-state-open:bg-surface-tertiary"
     >
-      <PlusCircle size={16} aria-label="Plus Icon" />
+      <PlusCircle size={16} aria-hidden="true" />
     </TooltipAnchor>
   );
 }