The invoice extraction module’s front-end code was reorganized to better follow development standards, making it easier to maintain over time. Users also get small interface improvements, including clearer active button styling on printed invoices and buttons that hide appropriately when switching to read-only mode.

The JS of this module has been re-written in order to follow JS
guidelines.

Also, this commit makes the following small improvements:

- 'active' button style on top of printed invoice
- buttons disappear when toggling mode from 'edit' to 'readonly'

Task-ID 1895515