* Update documentation images
* Introduce native vertical EPUB reader for Desktop
* Add libsecret support for Linux secret storage
* Update localized strings and plurals across multiple languages
* Update PDF annotation UI and highlighter settings on desktop
* Added support for right text alignment in epub reader
* Added tabs management to PDF navigation drawer
* Implemented unified selection menu placement logic
* Added reset functionality for toolbar customization
* Improved highlight filtering in epub pagination
* Migrated hardcoded UI strings to string resources
* Extracted desktop application logic from Main.kt into modular files
* Refactored Main.kt by extracting PDF and EPUB logic into specialized files
* Added Spanish language support
* Added system default option to app language selection
