[saloni-garg]

Fixes #47.

ListView is missing from the StrictWidgetComponent union in chatkit/widgets.py. It is only in StrictWidgetRoot, so a ListView works at the top level but not nested, even though ListViewItem is a strict component and containers like Card take list[WidgetComponent] children. The Widget Builder emits Card > ListView structures (example in the issue), and parsing one silently downgrades the list to a DynamicWidgetComponent: its typed fields (children: list[ListViewItem], limit, status, theme) are not validated and isinstance(child, ListView) is False for anything walking the tree.

This adds ListView to StrictWidgetComponent, next to ListViewItem, plus a regression test that parses the nested structure from the issue and checks the child comes back as a ListView with ListViewItem children.

Reproduced on current main:

• TypeAdapter(StrictWidgetComponent) rejects a valid ListView payload
• TypeAdapter(WidgetRoot) on a Card containing a valid ListView returns the child as DynamicWidgetComponent, not ListView

Tests: pytest tests/ is 130 passed on unpatched main (the new test fails), and 131 passed with this change.