feat(client): improve accessibility with ARIA labels and semantics

- Add aria-label to icon-only ActionIcon triggers across tree, comments,
  share, group, breadcrumbs, templates, AI chat, API keys, and spaces
- Give custom clickable divs/spans (color swatches, status swatches,
  load-more, PDF error, comment selection) role="button", tabIndex,
  and keyboard handlers
- Add listbox/combobox semantics (role, aria-selected, aria-activedescendant)
  to slash menu, emoji menu, mention list, and link editor results
- Add aria-haspopup/aria-expanded to bubble-menu triggers (node, text
  align, color) and status badge
- Add aria-label to Modal.Root/Dialog instances that lack a title prop
  (page history, template preview, trash preview, drawio, comment,
  find-and-replace, page verification)
- Add en-US translations for new aria-label strings

apps/client/src/features/share/components/share-action-menu.tsx

@@ -75,7 +75,7 @@ export default function ShareActionMenu({ share }: Props) {
         arrowPosition="center"
       >
         <Menu.Target>
-          <ActionIcon variant="subtle" c="gray">
+          <ActionIcon variant="subtle" c="gray" aria-label={t("More options")}>
             <IconDots size={20} stroke={2} />
           </ActionIcon>
         </Menu.Target>

apps/client/src/features/share/components/share-shell.tsx

@@ -148,6 +148,7 @@ export default function ShareShell({
                   onClick={toggleTocMobile}
                   hiddenFrom="sm"
                   size="sm"
+                  aria-label={t("Table of contents")}
                 >
                   <IconList size={20} stroke={2} />
                 </ActionIcon>
@@ -157,6 +158,7 @@ export default function ShareShell({
                 <ActionIcon
                   variant="default"
                   style={{ border: "none" }}
+                  aria-label={t("Table of contents")}
                   onClick={toggleToc}
                   visibleFrom="sm"
                   size="sm"