Complete localisation of all UI texts and extend CLI translation functionality

[tjementum]

Summary & Motivation

Localisation is extended to all UI texts, including new components such as the ThemeSelector, Help, and LocalSwitcher on the signup and login pages. The user's locale is now included in the UserInfo environment variable, and the LocalSwitcher has been updated to call the change-local endpoint, reloading the page with updated user profile info.

The User model has been updated with a Local property, and a new ChangeLocal command, handler, and API endpoint have been introduced to manage language preferences.

Danish translations have been added, and the UI texts have been updated based on feedback from Danish and Dutch translations.

The pp translate CLI command has been enhanced with additional options, allowing users to skip translations or exit and save collected changes during the process. All texts in the UI have been translated, and @lingui/macro is used in both TSX markup and code to prevent duplicate keys in .po files.

Checklist

• [x] I have added a Label to the pull-request
• [x] I have added tests, and done manual regression tests
• [x] I have updated the documentation, if necessary

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
17.6% Coverage on New Code
1.6% Duplication on New Code

See analysis details on SonarCloud