[Bug]: Current workflow tab can be (visually) deselected

### Prerequisites

- [x] I am running the latest version of ComfyUI
- [x] I have searched existing issues to make sure this isn't a duplicate
- [x] I have tested with all custom nodes disabled ([see how](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled))

### What happened?

Pretty much what it says in the title. The current active tab can be deselected by clicking on it with the mouse (or by keyboard while the button is focused). Not sure if this was introduced with the v3 UI or is an older bug, I just noticed it now due to experimenting with the new menu / tab placement options. This even happens if it's the only open tab.

https://github.com/user-attachments/assets/d2ea81c8-ccfc-4666-96d8-696a79fcfa08

It seems to be purely visual, if there are unsaved changes in the workflow, the indicator dot still disappears after saving even when deselected so the tab is still active.

### Steps to Reproduce

1. Open a workflow (a new unsaved workflow also works)
2. Click on the open tab
3. The tab gets deselected

### How is this affecting you?

Visual/UI issue only

### ComfyUI Frontend Version

1.26.5

### Browser

Chrome/Chromium

### Console Errors

```javascript

```

### Logs

```shell

```

### Additional Context

_No response_

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-5104-Bug-Current-workflow-tab-can-be-visually-deselected-2546d73d365081c9b977c26e84843fc8) by [Unito](https://www.unito.io)

Reproduce the issue in ComfyUI Frontend 1.26.5 using Chrome/Chromium: open a workflow, then click the current tab or activate it with the keyboard. Trace the frontend tab interaction from that behavior; it is done when the current workflow tab remains visually selected, including when it is the only open tab, without changing the existing workflow state.

Written by the indexing model from the issue text.