feat(editor): the simulation opens sheets, not windows in the window

A tap on a device in the simulation now only chooses it; its three-dot
button (or a long press) opens what Java's click opened: the desktop, and
newly a switch's SAT table and a home router's NAT table, beside each
card's data exchange.

The desktop, the tables and the data exchange are no windows in the
window any more but the simulation's sheet (SimulationSheet), after the
dashboard's AppSheet: below the toolbar to the bottom, a head with icon,
title, who else has it open, see-through and close. One at a time — it
covers the surface. It stays over a return to the design with the program
open on a desktop; a sheet whose device was removed closes. See-through
fades the body (0.55) and keeps the head; the choice is kept in the
browser. Java opens these as movable windows, several at once, with a
click; named in CHANGES.md.

Tests open through the menu (showFromMenu, showDesktop in editorPage.ts).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/editor/browser/gnutella.spec.ts

@@ -6,7 +6,7 @@
 // network left.
 
 import { expect, test, type Locator, type Page } from '@playwright/test';
-import { drawing, onDevice, openEditor, serveEditor } from './editorPage.js';
+import { drawing, onDevice, openEditor, serveEditor, showDesktop } from './editorPage.js';
 
 let server: { readonly base: string; readonly close: () => Promise<void> };
 
@@ -24,9 +24,7 @@ async function idOf(page: Page, name: string) {
 
 async function desktopOf(page: Page, name: string) {
   const id = await idOf(page, name);
-  const at = await onDevice(page, id);
-  await page.mouse.click(at.x, at.y);
-  return page.locator(`section[data-desktop="${id}"]`);
+  return showDesktop(page, id);
 }
 
 async function install(desktop: Locator, program: string) {
@@ -51,7 +49,7 @@ test('joins, searches and downloads as Java’s Gnutella window does', async ({
     (id) => (window as unknown as { filiusDev: { writeFile: (id: string, path: string, text: string) => void } }).filiusDev.writeFile(id, '/peer2peer/lied.txt', 'La la la'),
     otherId,
   );
-  await other.locator('.desktop-close').click();
+  await other.locator('.simulation-sheet__close').click();
 
   const desktop = await desktopOf(page, 'Rechner 1');
   await install(desktop, 'Gnutella');