Bump v6.0.0
* Add & update Weblate translations
* Add Bootswatch v5.3.3
* Add window.matchMedia mocking to setupTests.js
* Add Access-Control-Allow-Origin header globally
* Redirect to HTTPS if available
* Refactor Dark Mode
* Refactor index.scss & styles to match common Turris Bootstrap theme
* Refactor ThemeContext to improve theme handling and favicon change
* Refactor Header items to use icons with tooltips
* Refactor ErrorBoundary component for improved error handling and UI
display
* Set document language based on selected locale
* Other improvements in styles and code
* NPM audit fix