Minimax H3 Reference To Video node can have a sticky prompt override

### Custom Node Testing

- [x] I have tried disabling custom nodes and the issue persists (see [how to disable custom nodes](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled) if you need help)

### Expected Behavior

The Minimax H3 Reference To Video node with a primitive attached to the prompt field should always use the prompt in the primitive node.

### Actual Behavior

If the node had a prompt in it, then a primitive is attached, further prompt changes are overridden by the reference node's original prompt.

### Steps to Reproduce

As stated above. We can reproduce this with my supplied json. The original prompt "hiding" in the reference node is for a cat video, it should generally start with the cat sleeping on a little bed in a top view.
Load the workflow, and on the H3 reference node:
Unhook the video input.
Change the image to whatever.
Change the prompt to whatever.

On my end, regardless of these changes, the previews show the cat video being generated. Deleting the prompt primitive reveals the original cat prompt. I also notice that if instead of deleting the primitive, but disconnecting it via right click on the reference input, the prompt field on the reference node isn't restored, and the height input also becomes disconnected.

[H3_Ref_00010.json](https://github.com/user-attachments/files/30752389/H3_Ref_00010.json)

### Debug Logs

```powershell
n/a
```

### Other

_No response_

Load the attached H3_Ref_00010.json workflow and reproduce the sticky prompt behavior on the Minimax H3 Reference To Video node. Trace how the prompt primitive and the node's existing prompt are handled when the video input, image, prompt, and primitive connections change; done means the connected primitive value consistently takes precedence and disconnecting it restores the node inputs correctly.

Written by the indexing model from the issue text.