Model Swap Mid-convo provides little feedback & seems to silently override choice

### Short summary

Model Swap Mid-convo provides little feedback & seems to silently override choice

### Affected version or release

v1.0.24

### Installation context

_No response_

### What happened?

I often find I am pretty frustrated by the model selection UI and lack of feedback when changing model mid-convo.

I will want to swap a model as I realize the task isn't suitable or that I am running into compaction too quickly. Or sometimes get rate limited etc. As a result, I often want to swap the model. If you do this while the agent is reasoning, my selection is seemingly silently swapped back & it takes pausing, interrupting the convo, and like waiting 5 seconds (I probably am exaggerating) for my choice to get reflected. If I don't do this, it seems like my choice is never reflected & there isn't a clear signal on why/if I just need to wait etc.

I think mostly this makes sense but like having some indication that the change will go into effect would improve the experience / since it's unclear if there is an error or something else from my pov

### Steps to reproduce

1. Start convo
2. Swap model
3. Model choice isn't clearly pending & the model modal swaps back to the previous one.

### Expected behavior

I'd expect either my choice to be reflected OR a clear indication that my change is pending before the swap occurs

### Additional context

The payload names no files or tests. Start by locating the desktop app's model-selection UI and reproduce a model swap while the agent is reasoning; trace where the choice is updated and verify that the selected model remains visible or shows an explicit pending state.

Written by the indexing model from the issue text.