[Manager UI] “All Installed” shows no extensions although the backend returns installed packs

### Prerequisites

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

### What happened?

### Description

The native Manager UI displays “No Extensions Installed” under **Extensions → All Installed**, even though multiple active custom nodes are loaded successfully.

The backend is not empty:

`GET http://127.0.0.1:8188/api/v2/customnode/installed`

returns 8 installed packs with valid `cnr_id`, `aux_id`, version and enabled status. The corresponding Registry request also returns metadata for all 8 packs. Therefore, the frontend should display at least those 8 entries instead of an empty state.

The Registry startup synchronization completed successfully before retesting.

### Environment

- ComfyUI: 0.28.0
- ComfyUI Frontend: 1.45.21
- Native ComfyUI-Manager: 4.2.2
- Distribution: Windows Portable
- Python: 3.12.7
- Launch arguments: `--windows-standalone-build --enable-manager`

### Active custom nodes loaded at startup

- `comfyui_controlnet_aux`
- `ComfyUI_essentials`
- `ComfyUI-Custom-Scripts`
- `ComfyUI-Impact-Pack`
- `ComfyUI-LoRA-Pipeline`
- `ComfyUI-Misc-Utils`
- `ComfyUI-OpenPose-Studio`
- `ComfyUI-Styler-Pipeline`
- `ComfyUI-Ultralytics-Studio`
- `comfyui-inpaint-nodes`
- `rgthree-comfy`
- `was-node-suite-comfyui`
- `websocket_image_save.py` (standalone custom node)

### Expected behavior

“All Installed” should display every installed pack recognized by the backend, or at minimum the 8 packs returned by `/api/v2/customnode/installed`.

### Actual behavior

The page displays:

> No Extensions Installed
> You haven't installed any extensions yet.

A screenshot is attached.

### Steps to Reproduce

1. Disable legacy manager extension and enable the native one
2. Restart ComfyUI
3. Open the Extensions dialog

### How is this affecting you?

Feature doesn't work as expected

### ComfyUI Frontend Version

1.45.21

### Browser

Chrome/Chromium

### Console Errors

```javascript

```

### Logs

```shell

```

### Additional Context

## System Info
OS: win32
Python Version: 3.12.7 (tags/v3.12.7:0b05ead, Oct 1 2024, 03:06:41) [MSC v.1941 64 bit (AMD64)]
Embedded Python: true
Pytorch Version: 2.10.0+cu130
Arguments: ComfyUI\main.py --windows-standalone-build --enable-manager
RAM Total: 47.95 GB
RAM Free: 37.53 GB
Templates Version: 0.11.9

## Devices
- cuda:0 NVIDIA GeForce RTX 3060 : cudaMallocAsync (cuda)
VRAM Total: 12 GB
VRAM Free: 10.99 GB
Torch VRAM Total: 0 B
Torch VRAM Free: 0 B

Start in the Extensions → All Installed UI and trace how it loads data from GET /api/v2/customnode/installed and the corresponding Registry request. Compare the returned installed packs with the empty-state condition; done means the page displays the eight backend entries, with an appropriate test covering the populated response.

Written by the indexing model from the issue text.