Enhanced popup styles and improve click handling on FF mobile.

Add language detection and new tab options; refactor background and options scripts

I cleaned up the internal code to make the extension more stable and easier to maintain in the future.

The popup now opens faster. The extension loads and keeps the list of languages ready in advance, instead of loading it every time you open the popup.

The list of supported languages is now shared across the whole extension, which avoids duplication and reduces the risk of inconsistencies.

The extension can now automatically detect the language of the current page on its own.

You can press Ctrl+Shift+L (or Cmd+Shift+L on macOS) to automatically detect the page language and add the page to Aprelendo without choosing a language manually.

You can also right-click on any page and select “Add to Aprelendo (auto-detect language)” to do the same.

When you open the popup, the detected language is visually highlighted with a blue border to make it easier to confirm or change it.

Fix first-click issue in popup, prevent double tab creation, and improve cross-browser compatibility
- Added async message acknowledgement in background.js to prevent dropped messages on cold start (Chromium bug)
- Updated popup scripts to use a single 'pointerdown' handler with debounce to avoid double execution
- Ensured popup remains open until background confirms message
- Removed default focus outline causing dark border
- Improved accessibility and keyboard navigation (Enter/Space)

Minor fix to menu button margin and click listener

Now, Aprelendo opens in a new, separate tab, for improved navigation.

Minor fixes to popup menu:
- Fixed font size for mobile devices
- Click event listener now only works on popup buttons not its parents.

Minor fixes to options page and popup menu.

Added support for 14 new languages: Bulgarian, Catalan, Croatian, Czech, Danish, Hungarian, Norwegian, Polish, Romanian, Slovak, Slovenian, Swedish, Turkish and Vietnamese.

Minor fixes over last version.

- Added locales for Arabic, German, Greek, Spanish, French, Hebrew, Hindi, Italian, Japanese, Korean, Dutch, Portuguese, Russian and Chinese.
- Users can now add pages using a keyboard shortcut. Default language for this is set in Preferences.
- Improved Preferences look.

Added support for new languages and the ability to select which languages to show in the pop-up menu.

Added the possibility to choose the language of the text through a popup menu.

Added to support to add YouTube videos to your Aprelendo library.