NavigationRailTileSchema

Renders a Material 3 NavigationRail — the side-rail counterpart of NavigationBarTileSchema — with one NavigationRailItem per entry in items, plus 4dp horizontal and 8dp vertical padding applied by the renderer. An item is selected when its NavigationRailItem.id equals selectedItemId; the selected item's icon is drawn in its filled variant, the others outlined. NavigationRailItem.label is rendered centered under the icon, or omitted when null.

Header and footer: header is rendered in the rail's header slot above the items; footer is rendered at the very bottom, pushed down by a weighted spacer so it hugs the bottom edge. Both are arbitrary tiles and both are optional.

Selection: tapping an item dispatches a local NavigationRailTileEvents.OnItemClicked and the holder stores the new selectedItemId, so the highlight moves immediately without a server round trip. Tapping the already selected item still fires everything again.

Triggers dispatched:

• OnNavigationRailItemClickEventTrigger — fired when an item is tapped, carrying that item's NavigationRailItem.id, so events can be wired per item.

Notes: the rail itself is not clickable and fires no display trigger. It only tracks the selected item — performing the actual navigation is up to the events wired to the item clicks.