fix(vscode): use inert instead of aria-hidden on collapsed sidebar

aria-hidden only hides from screen readers; pointer-events: none only
blocks the mouse. Tab focus could still traverse into the hidden
sidebar's worktree buttons and session items. inert handles all three
at once: removes from the a11y tree, blocks pointer events, and prevents
keyboard focus.

packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx

@@ -2131,7 +2131,7 @@ const AgentManagerContent: Component = () => {
         class="am-sidebar"
         classList={{ "am-sidebar-collapsed": sidebarCollapsed() }}
         style={{ width: sidebarCollapsed() ? "0px" : `${sidebarWidth()}px` }}
-        aria-hidden={sidebarCollapsed()}
+        inert={sidebarCollapsed() || undefined}
       >
         <ResizeHandle
           direction="horizontal"

packages/kilo-vscode/webview-ui/agent-manager/agent-manager.css

@@ -40,7 +40,8 @@
   padding-right: 0;
   border-right-width: 0;
   overflow: hidden;
-  pointer-events: none;
+  /* Pointer events, focus, and a11y tree exclusion are all handled by the
+     inert attribute on the element. No need for pointer-events: none. */
 }
 
 .am-sidebar-collapsed > [data-component="resize-handle"] {