Fix sub-app permissions bug, add Comments app, support Site Editor

- Root-cause fix for "Sorry, you are not allowed to access this page" on
  Menu Creator/Activity Log/Role Editor: remove_submenu_page() was
  corrupting WP core's user_can_access_admin_page() capability lookup.
  Sub-apps now stay registered in $submenu; MenuSerializer filters them
  out of the sidebar instead.
- Add a 6th sub-app, Comments, with a redirect from native edit-comments.php.
- Extend the window-chrome/taskbar framing to the Site Editor
  (site-editor.php), including a fix for a CSS position:fixed
  over-constraint bug that let its frame run past the viewport.
- Rewrite the taskbar from a single sessionStorage slot to a list so
  multiple minimized windows are each independently restorable.
- Extend native-dark.css coverage to the block editor's own chrome.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

app/vite.config.js

@@ -29,6 +29,7 @@ export default defineConfig({
         'activity-log': fileURLToPath(new URL('./src/entries/activity-log.js', import.meta.url)),
         'database-explorer': fileURLToPath(new URL('./src/entries/database-explorer.js', import.meta.url)),
         plugins: fileURLToPath(new URL('./src/entries/plugins.js', import.meta.url)),
+        comments: fileURLToPath(new URL('./src/entries/comments.js', import.meta.url)),
       },
       output: {
         entryFileNames: '[name].[hash].js',