[Bug]: App Mode input panel pushed offscreen when output gallery becomes horizontally scrollable

### Prerequisites

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

### What happened?

When using the new app mode, generating a sufficient number of images to make a scrollbar appear on the output gallery at the bottom causes the right-hand inputs panel to be gradually pushed offscreen to the right.

### Steps to Reproduce

1. Set up app mode and switch to it
2. Generate enough images to fill up the bottom output gallery until a scroll bar appears
3. Next image gen pushes the input panel off the right-hand side of the screen.

### How is this affecting you?

Visual/UI issue only

### ComfyUI Frontend Version

1.48.6

### Browser

Firefox

### Console Errors

```javascript
p-splitter's minimum size is returned as 2371.5 px
```

### Logs

```shell

```

### Additional Context

Debugged with ChatGPT, which told me that the fix is:
```Diff
diff --git a/src/views/LinearView.vue b/src/views/LinearView.vue
--- a/src/views/LinearView.vue
+++ b/src/views/LinearView.vue
@@

```

And my temporary fix for now using a userstyle in Stylus is:
```css
nav.side-tool-bar-container + .p-splitter {
min-width: 0 !important;
}
```

It also told me that https://github.com/Comfy-Org/ComfyUI_frontend/issues/9508 may potentially be related.

Start in src/views/LinearView.vue and inspect the Splitter component's layout classes, then reproduce the issue in app mode by filling the output gallery until it scrolls horizontally. Verify that the inputs panel remains visible at the affected viewport sizes and that the console no longer reports an excessive minimum size.

Written by the indexing model from the issue text.