fix(windows): disable GPU sandbox to prevent startup crash

[rabindra789]

Summary

Fixes a startup crash on Windows 11 build 26200 where the GPU process repeatedly fails during initialization and Motrix exits before the UI becomes usable.

Issue: #1814

Problem

When launching Motrix normally on Windows 11 build 26200:

GPU process exited unexpectedly: exit_code=-1073741515
FATAL: GPU process isn't usable. Goodbye.

The application exits immediately.

Testing showed:

• --disable-gpu → still crashes
• --disable-gpu-sandbox → application starts successfully

Solution

Apply the equivalent of the working command-line workaround on Windows:

if (is.windows()) {
  app.commandLine.appendSwitch('disable-gpu-sandbox')
}

This change is Windows-only and leaves other platforms unchanged.

Testing

Environment:

• Windows 11 build 26200
• NVIDIA RTX 3050 Laptop GPU
• Motrix 1.8.19

Results:

• Application launches successfully
• Main window loads correctly
• Aria2 engine starts normally
• Downloads function normally
• Clean shutdown works

Notes

The exact underlying cause inside Chromium/Electron has not been identified. However, disabling only the GPU sandbox consistently resolves the startup failure.

Closes #1814