[FEAT] Support any emoji as folder icon as web does

### What would you like?

Folder icon should be any emoji available, not just a preset. Open WebUI already support this.

### Why do you want this?

To match existing Open WebUI functionality. Also for versatility and customization.

### Which platforms?

- [x] Android
- [ ] iOS

### Examples

_No response_

### How important is this to you?

Would be useful