🐛 `ScaffoldPage.padding` only apply at top

**Describe the bug**
When setting `ScaffoldPage.padding` to `EdgeInsets.all(100)`, it's only applied at the top of the content.

When looking at the code, it seems normal :
```
padding: widget.padding == null
? const EdgeInsetsDirectional.only(
top: kPageDefaultVerticalPadding,
)
: EdgeInsetsDirectional.only(top: widget.padding!.top),

```

**Expected behavior**
We would expect the padding to be applied completely

Locate the ScaffoldPage implementation and inspect the padding expression shown in the issue, starting with how widget.padding is converted to EdgeInsetsDirectional. Confirm that EdgeInsets.all(100) is applied on every side rather than only at the top, and verify the resulting layout with the existing ScaffoldPage usage or tests.

Written by the indexing model from the issue text.