Link Render Mode selection not saving between sessions

### Prerequisites

- [x] I am running the latest version of ComfyUI
- [x] I have custom nodes enabled

### What happened?

A somewhat small issue, but it has become annoying over time. After selecting a preferred link render mode (linear in this case), the setting is not saved between sessions. The next launch it reverts to the default spline mode. This in on a working portable Comfy installation. It would be great if this could be saved to persist across sessions.

### Steps to Reproduce

1. Change Link Render Mode to something other than spline in settings
2. Close ComfyUI
3. Relaunch ComfyUI
4. Links show as spline style, not the other selected style

### How is this affecting you?

Visual/UI issue only

### ComfyUI Frontend Version

1.38.13

### Browser

Firefox

### Console Errors

```javascript

```

### Logs

```shell

```

### Additional Context

_No response_

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-8906-Link-Render-Mode-selection-not-saving-between-sessions-3096d73d365081b4a1b4f76491f85f26) by [Unito](https://www.unito.io)