Subgraph: Text fields persist as "ghost" elements on workspace when subgraph is minimized

### Description

When a subgraph containing text field widgets is minimized, the text fields remain visible on the workspace as "ghost" elements. They appear overlaid on the canvas even though the subgraph is minimized.

### Steps to Reproduce
1. Create a subgraph containing nodes with text input widgets
2. Open the subgraph so text fields are visible
3. Minimize (fold) the subgraph
4. Observe the text fields remain on the workspace

### Expected Behavior
All widget elements inside a subgraph should be hidden when the subgraph is minimized.

### Actual Behavior
Text fields persist as ghost elements on the workspace after minimizing.

### Environment
Tested on Chrome and Firefox across two different operating systems. Reproduced with cleared browser data.

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*Split from #9979*

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-9994-Subgraph-Text-fields-persist-as-ghost-elements-on-workspace-when-subgraph-is-minimi-3256d73d36508187bf92ffc4f0723464) by [Unito](https://www.unito.io)