fix(desktop): report real hostname/platform/arch in heartbeat

Renderer was registering clients with navigator.platform ("MacIntel") and
a hardcoded "renderer-preview" cpu_arch. Source device info from the main
process (os.hostname + process.platform/arch) via a new device-info IPC,
and let heartbeats always send the authoritative runtime values so stale
registrations self-heal.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/desktop-client/src/main/bootstrap.ts

@@ -1,3 +1,4 @@
+import { hostname } from "node:os";
 import { join } from "node:path";
 
 import { BrowserWindow, WebContentsView, app, ipcMain, nativeTheme } from "electron/main";
@@ -125,6 +126,11 @@ function safeHandle<Args extends unknown[], Result>(
 
 function registerBridgeHandlers(): void {
   ipcMain.handle("desktop:ping", () => "pong");
+  ipcMain.handle("desktop:device-info", () => ({
+    device_name: hostname() || `Desktop ${process.platform}`,
+    os: process.platform,
+    cpu_arch: process.arch,
+  }));
   ipcMain.handle("desktop:runtime-snapshot", () => createRuntimeSnapshot());
   safeHandle("desktop:bind-publish-account", async (_event, platformId: string) => {
     const account = (await bindPublishAccount(platformId)) as DesktopAccountInfo;