Hidden file affects the position of the icon and cause layout confusion

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```json
{
"title": "Test Application",
"icon": "test-app.icns",
"background": "test-background.png",
"contents": [
{ "x": 448, "y": 344, "type": "link", "path": "/Applications" },
{ "x": 192, "y": 344, "type": "file", "path": "/Applications/TestApp.app" },
{ "x": 5000, "y": 0, "type": "position", "path": ".VolumeIcon.icns" },
{ "x": 5000, "y": 0, "type": "position", "path": ".background" },
{ "x": 5000, "y": 0, "type": "position", "path": ".DS_Store"}
]
}
```

If contents contains items with "type": "position"

1. Will affect the x and y values in "type": "file" and "type": "link".
2. When the user uses the shortcut keys `command + shift + .` to show/hide files, it will cause layout confusion. (If it doesn’t happen again, you can exit dmg and reopen it)

Reproduce the layout using the shown contents configuration, including the position entries for hidden files, then toggle hidden files with Command+Shift+. Check how position items affect file and link coordinates and how hidden-file visibility changes are handled. Done means hidden entries no longer shift visible icons or create layout confusion.

Written by the indexing model from the issue text.