Remove PWA functionality and service worker infrastructure

Completely remove Progressive Web App features including VitePWA plugin, service workers, install prompts, and platform service PWA methods. Delete PWA component, service worker files, help images, and update build configurations. Simplify application architecture by removing PWA complexity while maintaining core functionality.

src/services/platforms/ElectronPlatformService.ts

@@ -166,7 +166,4 @@ export class ElectronPlatformService extends CapacitorPlatformService {
 
   // --- PWA/Web-only methods (no-op for Electron) ---
   public registerServiceWorker(): void {}
-  public get isPWAEnabled(): boolean {
-    return false;
-  }
 }