[UI/UX] Guide first-time users with the start screen

[HugoGenillier]

The most impactfull recommandation established after the UI/UX study on score is having an appealing starting phase for beginners.

Start screen :

The first impression on score comes with the start screen. This one deserves to be clearer with a better organization than a list of buttons. Some names may need to changed or to be more explicit such as "New" which will be more clear if a term was used to define a score project like "New score" or "New project". To give an idea : some research were made in this [Figma mockup](https://www.figma.com/design/Z887oNMLuUsY8BjoJCsdkp/Interactive-Ossia-Prototypes?node-id=286-107&t=gc08hlrGojgG7t3B-1.

The idea is to organize and create a visual hierarchy so that even a first time user understands each part of the start screen. And can easily see every ressources he can have access to. Indicating a clear and single path for newcomers such as ‘if you’re new to ossia you can do this : …’ is a goal to achieve in order to introduce beginners properly and hopefully retain them after the first use.

Also some fix can be applied such as adding a cross icon on the top right that on click closes the start screen and by default opens a new score and closes the start screen. And replacing the current ‘Exit’ button by an ‘Exit ossia score’ button on the bottom of the start screen.

This recommandation was judged as one of the most impactfull but requieres an effort to be implemented.

[jcelerier]

@aklevy what are your thoughts ?