fix: enable background update checks in dev builds

Remove the isPackaged guard from AutoUpdateService.start() so that
background update checks run in both packaged and dev builds.
forceDevUpdateConfig already handles dev-mode config correctly via
dev-app-update.yml — the start() gate was preventing the 10s initial
check and 4h periodic checks from ever being scheduled in dev.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/main/services/autoUpdater.ts

@@ -192,7 +192,7 @@ export class AutoUpdateService {
   }
 
   start(): void {
-    if (this.started || !this.options.isPackaged) {
+    if (this.started) {
       return;
     }