feat: add back button in setup screen

[im-adithya]

Fixes #310

Screenshot

[rolznz]

@im-adithya this is for Wails/Desktop mode where it has no browser navigation, so shouldn't we always have a back button in that case (on every page)?

Therefore, it also doesn't need to be shown in non-desktop mode

[im-adithya]

It felt weird to have a back button in /welcome and /setup/finish as there is no point in navigating there.

Is that what you mean or you mean for all pages in general? I only added the back button here because in all the other places we either provide breadcrumbs or the sidebar for the user to go to the previous page. Shouldn't that be good?

[rolznz]

@im-adithya sounds good and fixes the main issue. But I think we should whitelist, not blacklist pages since you missed some:

[rolznz]

@im-adithya I pushed a fix, can you check it?

[rolznz]

tACK

[im-adithya]

I pushed a fix, can you check it?

Looks better now, thanks!