Not launching the game in fullscreen

```
{
"CVars": {
"Fullscreen": {
"Enabled": 1
},
```

Is not launching the game in fullscreen.

Start by reproducing the launch with the provided CVars configuration and verify whether the Fullscreen.Enabled setting is read during startup. Trace the game's startup and window-display entry points to find where fullscreen is applied, then confirm that launching with this setting enabled opens the game in fullscreen.

Written by the indexing model from the issue text.