Release v0.4.0

Added

• aggregateContributions() (@cratis/scene.engine) - collects every contribution targeting a given contribution point, ordered ascending by its explicit order (unordered contributions sort after every ordered one, in their original relative order). Resolving which contribution point a contribute to targets already happens before a Contribution exists in Scene.Model (see its own doc comment), so there was no ambiguity left for the engine to resolve here, only ordering - this is narrower than the issue's original proposal, which assumed the engine would still walk a nearest-enclosing resolution; that already happened upstream. (#2)
• NavBar widget (@cratis/scene.react) - renders the aggregated Navigation contributions. How navigate to <Screen> becomes a concrete route is a caller-supplied renderRoute callback rather than a fixed URL scheme, so the same widget works unmodified across renderers, per the issue's own "configurable per renderer" requirement. (#2)
• extractNavigationItem() - reads a NavigationItem out of a Navigation contribution's ExternalComponent.properties bag.

Notes

extractNavigationItem's property-bag key contract (label, targetScreen, routeParameterBindings, order, group - the same names as NavigationItem's own fields) is a Scene#2 design choice made without a real Screenplay-to-Scene translation to confirm it against - Stage#37 (the Screenplay → Scene seam) hasn't been built yet. Documented as an assumption in the function's own doc comment; Stage#37 should either match this contract or this function should move to match whatever it actually emits.