ui: hide case folder display from bottom toolbar

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/web/public/index.html

@@ -200,8 +200,8 @@
           </div>
         </div>
 
-        <!-- Directory -->
-        <div class="toolbar-group">
+        <!-- Directory (hidden) -->
+        <div class="toolbar-group" style="display: none;">
           <button class="btn-toolbar" onclick="app.toggleDirInput()" title="Set working directory">
             <span id="dirDisplay">No directory</span>
           </button>