Apr 11: I'm putting this on the backlog for now, since we may not need a toolbar component in the short term after all. The motivation for this was that we might need different modes of operation if we want the visualizer to behave differently when nodes are clicked depending on the mode (e.g. SelectPaths vs setting/changing values for what-if evaluation). But another option might be to use a different UI/UX for select paths.

We can return to this once we make some mock-ups and get some feedback from the rest of the team.

In the short term I think the following kind of menu should be good enough.

Either

• Combo box | zen mode switch where | is a visual separator. The combobox should have a ‘Mode’ label, with 'Select Paths' and '#WhatIf' as the options in the short term

or

• a menu with 'Select Paths' and '#WhatIf' tools / buttons, and the zen mode switch with a separator (and where it's not possible to select both the paths and whatif button).

I recommend using (the svelte 5, 'next' version of) shadcn svelte if possible. I use it in #252 --- you can check that out to see where I’ve put the shadcn svelte ui primitives.

No need to worry about wiring it up to anything — just focus on the layouting and css and I can take care of the rest.

Further sub-tasks

• @johsi-k to look into whether z-[9999] really is a good idea -- feels like a hack to me
• Refactor the toolbar to make it clash a bit less visually with the rest of the flow stuff
• YM will think more about where in the component hierarchy the Toolbar should be used
• YM will check where Toolbar.svelte should be put