[UI] Unclear that graphs cannot be reordered

### What happened?

With multiple graphs, when I drag graphs up/down with their drag handle it does not seem to actually reorder.

### What was the expected functionality?

reorder the graphs

### Describe your environment

MacOS

### Relevant log output

```shell
none
```

### Relevant screenshots

https://github.com/Ironclad/rivet/assets/293802/af99e73c-a3c7-41b8-8ba2-fa6ee027e76d

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct

Start by reproducing the issue in the UI with multiple graphs and the graph drag handle, using the linked screenshot as context. Trace the graph ordering interaction from that entry point; done means dragging a graph visibly changes its order and the resulting order remains correct.

Written by the indexing model from the issue text.