feat(editor): F4.6a simulation mode and a computer's desktop

Java's mode buttons start and stop the room, now in a worker of the
editor's page (LocalSimHost), with Java's speed slider. While the
simulation runs the design is locked as in Java: no palette, no sheet,
nothing moves, no undo. Cables that carry a frame light up in Java's
green, and a tap on a computer opens its desktop: Java's title, the
software installation first, then the installed programs in the order
of Java's list for the language, a taskbar with the network icon and
the network as the simulation runs it. The room sends that over a new
topic, node:<id>. Desktops stay over a return to the design and show
again at the next start. The programs' windows follow from F4.6b.

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

packages/editor/browser/editorPage.ts

@@ -6,7 +6,7 @@ import { dirname, join } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import type { Page } from '@playwright/test';
 import { build, preview, type PreviewServer } from 'vite';
-import type { DeviceSheet, TopologyView } from '@mdg-filius/doc';
+import type { DesktopView, DeviceSheet, TopologyView } from '@mdg-filius/doc';
 
 const config = join(dirname(fileURLToPath(import.meta.url)), '../vite.config.ts');
 
@@ -35,6 +35,11 @@ export function sheetOf(page: Page, id: string): Promise<DeviceSheet | undefined
   return page.evaluate((each) => (window as unknown as { filiusDev: { sheet: (id: string) => DeviceSheet | undefined } }).filiusDev.sheet(each), id);
 }
 
+/** What a computer's desktop reads of the document. */
+export function desktopOf(page: Page, id: string): Promise<DesktopView | undefined> {
+  return page.evaluate((each) => (window as unknown as { filiusDev: { desktop: (id: string) => DesktopView | undefined } }).filiusDev.desktop(each), id);
+}
+
 /** A device's button as data-box says it (surface pixels). */
 export async function boxOf(page: Page, id: string): Promise<{ x: number; y: number; width: number; height: number }> {
   const [x, y, width, height] = (await page.locator(`g.device[data-node="${id}"]`).getAttribute('data-box'))!.split(' ').map(Number) as [number, number, number, number];