feat(security,build): add COOP/COEP headers and improve PDF viewer initialization

- Add Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy headers to nginx.conf for enhanced security
- Create serve.json configuration file with security headers for local development
- Update npm scripts to use vite preview instead of serve package for consistency
- Fix PDF viewer file parameter handling to prevent fallback to default URL
- Enable annotation editor mode by default in PDF viewers (annotationEditorMode: 1)
- Improve PDF preference management by clearing conflicting annotation editor settings before loading
- Update iframe URL construction to use URL API for proper origin handling
- Refactor annotation viewer setup to use eventBus for stamp button activation instead of direct DOM manipulation
- Add localStorage preference configuration for signature editor and permissions in sign tool
- Enhance security posture by implementing COOP/COEP headers required for SharedArrayBuffer and cross-origin isolation

src/js/main.ts

@@ -5,6 +5,7 @@ import { createIcons, icons } from 'lucide';
 import * as pdfjsLib from 'pdfjs-dist';
 import '../css/styles.css';
 import { formatStars } from './utils/helpers.js';
+import '../version.js';
 
 const init = () => {
   pdfjsLib.GlobalWorkerOptions.workerSrc = new URL(