one gallery editor, in both places

GalleriesPanel drew its own copy of the item list — same operations, same routes,
arrows instead of a grip. It is a master list now: which galleries there are,
making one, deleting one. What is inside the selected one is announced to the
editor column and drawn by GalleryItems, which is what a gallery BLOCK already
used.

The device toggle only shows where there is a page to look at. It sets the width
the preview renders at, and Galleries, Media and Administration have none.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/EditorPanel.tsx

@@ -59,10 +59,21 @@ export const EditorPanel = () => {
         </div>
       )}
 
-      {/* Outside the scroll area, so a long editor cannot carry it off the screen. */}
-      <div className="shrink-0 border-b border-border px-3 py-2">
-        <DeviceToggle />
-      </div>
+      {/*
+        Only where there is a page to look at.
+
+        The toggle sets the width the PREVIEW renders at, and Galleries, Media and Administration have
+        no preview — the control would be three buttons that do nothing visible. Named here rather
+        than read from `usePreviewable`, which is a context inside the detail panel and this is its
+        sibling.
+
+        Outside the scroll area, so a long editor cannot carry it off the screen.
+      */}
+      {(section === 'layout' || section === 'pages') && (
+        <div className="shrink-0 border-b border-border px-3 py-2">
+          <DeviceToggle />
+        </div>
+      )}
 
       {editor ? (
         /*