virtio-ramfb-gl crashes with NativeResolution=true (Neptune context destroyed)

## UTM v5.0.5: `virtio-ramfb-gl` crashes with `NativeResolution=true`

### Environment

* **UTM:** 5.0.5 (Beta)
* **macOS:** macOS Sequoia, Darwin 24.x
* **Hardware:** Apple Silicon MacBook Pro, M1 Pro, 32 GB RAM
* **VM:** QEMU, `aarch64`, `virt` machine
* **Display:** `virtio-ramfb-gl`
* **Guest:** Windows 11 ARM64, build 26100.x
* **Guest tools:** UTM Guest Tools installed, including SPICE agent and VirtIO drivers

### Issue

I found that the VM consistently crashes when `NativeResolution=true` is enabled with the `virtio-ramfb-gl` display.

### Steps to reproduce

1. Create a Windows 11 ARM64 VM using QEMU `aarch64` and the `virtio-ramfb-gl` display.
2. Install Windows and UTM Guest Tools.
3. Shut down the VM.
4. Enable `NativeResolution=true` and `DynamicResolution=true`.
5. Test with both `Nearest` and `Linear` for the upscaling and downscaling filters.
6. Start the VM.

### Expected result

The VM should start normally and use the Mac's native Retina resolution.

### Actual result

QEMU crashes during startup with:

```text
QEMU error: QEMU exited from an error:
QEMURenderServer: npt: destroying Neptune context
```

After this happens, Windows can also enter the Recovery screen on the next boot.

### Tests

| Upscaling | Downscaling | Native Resolution | Dynamic Resolution | Result |
| --------- | ----------- | ----------------- | ------------------ | --------- |
| Linear | Linear | false | true | OK |
| Nearest | Nearest | false | true | OK |
| Nearest | Nearest | **true** | true | **CRASH** |
| Linear | Linear | **true** | true | **CRASH** |

I tested both scaling filters, and the result is the same in both cases. The VM works when `NativeResolution=false` and crashes when it is changed to `true`.

Based on these tests, the problem seems to be related to `NativeResolution` rather than the scaling filters. The crash also appears to happen in the QEMU rendering process when Neptune creates or handles the rendering context at the higher Retina resolution.

### Configuration that works

This is the configuration I am currently using:

```xml
DownscalingFilter
Nearest
DynamicResolution

Hardware
virtio-ramfb-gl
NativeResolution

UpscalingFilter
Nearest
```

With `Nearest`, text and UI elements look sharper to me than with `Linear`, which tends to look slightly blurry.

No source file, test, or entry point is named. Reproduce the Windows 11 ARM64 QEMU setup with virtio-ramfb-gl and compare NativeResolution=false and true using both filter pairs; done means the VM starts with NativeResolution=true without the Neptune context crash.

Written by the indexing model from the issue text.