GUI v2: Implement the new Dangerzone GUI designs

[apyrgio]

Background

We want Dangerzone to be a tool that does one thing well (give it a document, get back a sanitized copy), and then get out of the way. This is a statement that is conceptually simple, but very hard to apply it in the real world. We need Docker/Podman to make conversions work, settings that the user needs to tweak, proper error messages, etc. Most importantly though, we want to present those features and capabilities in an intuitive way.

Why even spend resources on that? Because an app that is easy to use and hard to misuse, is a safer app. Safer than most security measures we can think of (and we have applied a lot of those in the past few months)

That's why we collaborated with designers from Superbloom and Okthanks. The considerations we presented to the designers are based on our research we conducted on 2023 on IJF, GitHub issues that Dangerzone users have created (keep 'em coming!), and untapped workflows that us devs have identified.

We have tried to come up with a new look and feel that will not alienate users, and will be simple to implement.

Don't bore us, get to the chorus

Here's the design material that we will work with:

• Dangerzone UI v2 (.svg)
• Dangerzone UI v2 (.png)
• Design system and UI elements (.svg)
• Design system and UI elements (.png)

Right from the start, you can see the following new features:

• Welcome page
• Add files after a conversion has started
• Instant file previews (see also File Preview PoC #758)
• Conversion logs
• Per-document settings
• Estimated conversion time

Tasks

In this section we'll track all the GitHub issues that are related with the GUI redesign. Please label those with the gui-v2 and enhancement labels.

• GUI v2: Footer #886
• GUI v2: Welcome page #887
• GUI v2: Alert popup #888
• GUI v2: Default settings #889
• GUI v2: Document pop-up #890
• GUI v2: Document row #891
• GUI v2: Drag-and-drop interface #892
• GUI v2: Document conversion interface #893

For a speed run through those issues to an MVP that can be used by our users, take a look at #894.