Add use cases with interactive tour

[nesnoj]

For better understanding the app, some (3-4) use cases / how-tos from the stakeholder exchange will be defined. Example: "What areas are available for PV in my municipality?"
Click goes to step using the tour function, explains and activates elements. I think this should be easy as this is basically similar to functionality in #58? @henhuy

@bmlancien Where's a good place to show those use cases? I thought about step 1 or the top menu, the latter promotes visibility and accessibility.

[bmlancien]

I think both places are fine, although having it on the top menu is a good idea if we consider it to be an essential feature for comprehension throughout the app and want it to always be within reach.

[bmlancien]

@nesnoj Here are two versions of how it could look like:

1. Green
   

2. Blue
   

I prefer the blue version, as it is more consistent with the overall color scheme of the app. It is visible enough but not too much. I think the main interactive elements, such as the navigation buttons, should still stay on the foreground, as they are necessary elements users need to click. On the other hand, use cases buttons are optional.

[nesnoj]

Thx for the proposal, I prefer the blue one too! Please implement :)

• Please add 3 instead of 2 use cases
• In the screen for step 4, clicking will open the dropdown/reveal within the sidepanel, right?