fix(native): offer one "Files" row in the new-tab list

The editor type's page identity IS the `files` kind takeover (same
explorer, same title), so the guide/new-tab list showed two identical
"Files" entries — observed on a real profile after the takeover landed.
The editor type now contributes no guide entry of its own; it stays
registered as the file RESOURCE viewer. Covered by the registration
lifecycle test (editor: no guide, files takeover: guide).

src/client/native/index.ts

@@ -160,7 +160,11 @@ export function registerNativeSurface(deps: NativeSurfaceDeps): () => void {
         // A resource tab is titled by the file it shows; a page tab keeps the
         // descriptor's own title.
         title: (address: string) => (isEditor ? fileTitleOf(address) ?? titleOf(descriptor) : titleOf(descriptor)),
-        ...(descriptor.hidden === true
+        // No guide entry for the editor: its page identity is the `files`
+        // kind takeover below (same view, same title), so listing both would
+        // offer the reader two identical "Files" rows. The type itself stays
+        // registered as the file RESOURCE viewer.
+        ...(descriptor.hidden === true || isEditor
           ? {}
           : {
             guide: [{