ScrollAwareFloatingActionBar class

A layout helper that overlays a floating action bar above a scrollable body.

The widget keeps the bar visibility logic close to the layout instead of duplicating it in each screen:

1. Scrolling toward larger offsets hides the bar
2. Scrolling back toward the top shows the bar
3. Reaching the top always shows the bar
4. Tapping the body toggles the bar visibility
5. Swiping horizontally to change pages reveals the bar when hidden

The floatingActionBarBuilder receives the resolved visibility state so the caller can decide whether to render a FloatingActionBar or omit the bar entirely for the current screen state.

Example:

ScrollAwareFloatingActionBar(
  floatingActionBarBuilder: (context, visible) => FloatingActionBar(
    visible: visible,
    child: ChipTabSwitcher(
      tabs: const ['114-2', '114-1', '113-2'],
    ),
  ),
  child: ListView.builder(
    itemCount: 20,
    itemBuilder: (context, index) => ListTile(
      title: Text('Row $index'),
    ),
  ),
)