Graph Editor / Viewer: Value changes do not update if shader recompile is required

Changes to input values which actually are topological changes which require the shader to be rebuilt are not caught -- resulting
in the appearance of not working. Value changes currently directly modify shader inputs for efficiency.

This does not necessarily apply to all backend targets but any that call C++ to generate new code such as conditionals.
Enumerants also will fall into this category if a single choice is encoded when generating (e.g. such as image node texture addressing.
Value changes which affect transparent display may also not be caught.

e.g. is a graph with a switch node where a change in the `which` selection input will result in nothing updating.
```xml

```

if the condition is being fed by an interface input, then changes at the interface level which affect a conditional should be considered, though a full downstream traversal could be "expensive" at least the first level interface should work.
e.g.
which would be this graph:
```xml

```

Reproduce the issue in the Graph Editor/Viewer with the provided switch-node and conditional-graph XML examples, then trace how input value changes are handled when shader regeneration is required. Verify the behavior across affected backend targets, including enumerants, transparent-display changes, and first-level interface inputs; done means the displayed result updates after each relevant change.

Written by the indexing model from the issue text.