feat: implement offline fonts support (v0.1.4)

- Add local font files to public/fonts directory
- Replace Google Fonts CDN with local @font-face declarations
- Include both regular and italic variants for preview fonts
- Remove unused editor italic fonts to reduce bundle size
- App now fully functional offline without external dependencies
- Total font bundle: ~22.8 MB (10 font files)

package.json

@@ -1,7 +1,7 @@
 {
   "name": "nextcloud-notes-tauri",
   "private": true,
-  "version": "0.1.3",
+  "version": "0.1.4",
   "type": "module",
   "scripts": {
     "dev": "vite",