BitmapImage URI download hangs indefinitely when network drops mid-transfer

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### Describe the bug

Component: https://learn.microsoft.com/en-us/uwp/api/windows.ui.xaml.media.imaging.bitmapimage

When a BitmapImage is loading from an HTTP URI and the network connection drops after the request starts, the download hangs forever and `ImageFailed` never fires. The BitmapImage remains in a permanent loading state. Even after the network recovers, the stalled download does not resume or error out.

### Why is this important?

In our application, we display a grid of ~20 images loaded from CDN URLs. If a user's network briefly drops or becomes unstable mid-load, the affected images show infinite loading spinners that never resolve. We want to remove the pending image downloads from UI in such cases or show an error but since `bitmap.ImageFailed` doesn't fire there doesn't seem to be a documented way to do so.

### Steps to reproduce the bug

1. Create a `BitmapImage` and set UriSource to a valid HTTP URL (use a large image or throttled server for easier repro).
1. Wait for the HTTP request to start
1. Disconnect the network
1. Wait 20+ minutes. Observation: ImageFailed never fires.
1. Reconnect the network. Observation: the stalled download does not resume or fail, it remains stuck indefinitely.

### Actual behavior

The pending image downloads get stuck in an infinite loading state on a network drop.

### Expected behavior

Either:
- [ImageFailed](https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.media.imaging.bitmapimage.imagefailed) should fire after a (configurable?) timeout when the underlying HTTP transfer stalls so based on it we can retry, show an error state, or clean up. The download should not hang silently forever.
OR
- Once the network reconnects, the pending download should resume/retry and fetch the complete image.

### Screenshots

_No response_

### NuGet package version

Microsoft.WindowsAppSDK 1.6.250108002

### Windows version

Windows 11 (25H2): Build 26200

### Additional context

_No response_

Start by reproducing the issue with a BitmapImage loading a large HTTP image, then disconnect the network after the request begins and observe ImageFailed and recovery behavior. Trace the BitmapImage image-download path and its handling of stalled transfers. Done means a stalled download either raises ImageFailed after a defined timeout or resumes/retries after connectivity returns.

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