[Bug]: Splitting existing transaction causes UI glitches as splits disappear and reappear

### Verified issue does not already exist?

- [x] I have searched and found no existing issue

### What happened?

I'm not sure how to best summarize the issue, so excuse the awkward title. Splitting an existing transaction seems to cause some kind of synchronization weirdness and makes the UI glitch, as the split transactions disappear and reappear.

Once I'm done splitting the transactions, I'm also left with a 0.00 split transaction.

https://github.com/user-attachments/assets/32325703-1880-40bf-b5f0-d06a3058371d

Just for clarity, in the video I press enter after entering the amount and then I don't press or click anything at all (until you see my start typing again).

None of this happens when creating a new transaction as a split transaction straight away.

### How can we reproduce the issue?

I've been able to reproduce this on the demo instance, but it's not as pronounced there, likely because the demo instance has much fewer transactions.

1. Create a transaction as a non-split transaction
2. Edit the transaction category to turn the transaction into a split transaction
3. Enter the first split amount, press Enter
4. Observe glitchy UI behavior

### Where are you hosting Actual?

Docker

### What browsers are you seeing the problem on?

Firefox

### Operating System

Linux