Allow seeing available nodes and adding them to the flow

[bakoe]

For instance, an additional pane or some kind of context menu could be used. Make sure that the interaction is clear on mobile devices as well.

UI/UX Ideas

• Right-click/Long-press on flow editor background/WebGL scene background(?) → Context menu with (fuzzy) search and/or grouping of nodes into categories → Respective node get added to the scene
• Additional pane with (fuzzy) search and/or grouping of nodes into categories → User clicks/taps or drag-and-drops such a node into the scene → Respective node get added to the scene
• Clicking/tapping/dragging from a handle of an existing node → Creation of (empty) placeholder node (immediately visualized) → Selection of node type (of already created placeholder node)