When Subgraph unpacked, removing AutoGrow links on multi-spec nodes (Math Expression); Batch Images remain unaffected.

### Prerequisites

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

### What happened?

When a node that uses a **multi-spec autogrow input** (an `io.Autogrow.Input` combined with at least one other input/widget) is placed inside a subgraph / group node and then **unpack Subgraph**, the autogrow links beyond the first slot are silently dropped. **Single-spec autogrow nodes are unaffected.**

I verified this side-by-side with a screen recording comparing two official nodes:

- **Batch Images** (`BatchImagesNode`) — single autogrow input `images` → **no link loss** after ungroup.
- **Math Expression** (`ComfyMathExpression`) — autogrow `values` + a `expression` widget → after ungroup, the **3rd input (`values.c`) link is disconnected**; `a` and `b` survive.

### Steps to Reproduce

https://github.com/user-attachments/assets/3710b000-167b-4b95-b0c0-00320eb0a2f4
1. Add a **Math Expression** node plus three source nodes (e.g. three primitive/value nodes).
2. Connect all three into `values.a`, `values.b`, `values.c`.
3. Select all and **Convert to Subgraph / Group Node**.
4. **Unpack the subgraph back to nodes**.
5. Observe: `values.c` is disconnected.

**Control:** repeat steps 1–4 with **Batch Images** (single autogrow `images`) fed by 3 image sources → all links survive ungroup.

### Workflow

[Unsaved Workflow.json](https://github.com/user-attachments/files/31611958/Unsaved.Workflow.json)

### How is this affecting you?

Feature doesn't work as expected

### ComfyUI Frontend Version

1.49.6

### Browser

Chrome/Chromium

### Console Errors

```javascript

```

### Logs

```shell

```

### Additional Context

_No response_