v0.2.0 — Screen Flow & Loading Flow Sample

Added

• Screen flow system (Runtime/Flow/). A stack-based screen navigator with full lifecycle:
  PushAsync, PopAsync, ReplaceAsync, PopToRootAsync, PopAllAsync. Screens are UXML
  documents managed by presenters with lifecycle hooks: OnBindAsync, OnActivate,
  OnDeactivate, OnSuspend, OnResume, OnBackRequested. Model-parameterized variants
  (PushAsync<TPresenter, TModel>(model)) pass data to a screen at open time.
  • ScreenNavigator — the stack, per-scene scoped via VContainer.
  • BaseUIToolkitScreenPresenter<TView> / <TView, TModel> — presenter bases.
  • BaseUIToolkitPopupPresenter<TView> / <TView, TModel> — popup convenience with Close().
  • ScreenOptions — None (full screen), Modal (overlay layer), DimsBelow (dims without
    suspending the screen below).
  • ScreenSubscriptions — scoped cleanup for button clicks and events.
  • ScreenRegistry — maps presenter type to view type, asset key, and options.
  • ScreenLifecycleState — 9 states from Registered to Disposed.
  • IScreenScopeFactory / VContainerScreenScopeFactory — one VContainer child scope per screen.
  • ScreenFlowRegistration — RegisterUIToolkit(), RegisterScreenFlow(),
    RegisterScreen<T,V>(), RegisterPopup<T,V>() extension methods for VContainer.
• Back navigation (Runtime/Input/BackNavigationSource). Wires Escape, gamepad B, and
  Android back to the navigator. One-line setup: source.BackHandler = navigator.HandleBack.
  RootBackPolicy controls what happens at the bottom of the stack: NotHandled (platform
  default), Consume (swallow), or Raise (event).
• Assembly definitions for all samples. Samples could not compile when imported via Package
  Manager because they had no .asmdef. Each sample now ships its own.
• Loading Flow sample (Samples~/LoadingFlow). Two-scene flow demonstrating every package
  feature: LoadingScene (MonoBehaviour-driven progress bar with tips and spinner) transitions to
  MainScene (ScreenNavigator with Push, Pop, Replace, PopToRoot, Modal+DimsBelow overlay, model
  parameters, lifecycle hooks, OnBackRequested override, BackNavigationSource,
  UIToolkitListAdapter collection adapter, and per-scene navigator scoping).
• A DOTS/ECS presentation adapter (Runtime/Ecs/), optional behind com.unity.entities
  and the CUVARA_UITOOLKIT_ENTITIES versionDefine.
  • IViewModelSink<TViewModel> — the contract a host's Presenter implements.
  • EcsViewModelBridge<TComponent, TViewModel> — managed SystemBase in
    PresentationSystemGroup that converts component data to a plain ViewModel.
  • EcsSinkRegistration — binds a sink for a screen's lifetime and unbinds on Dispose.
  • Samples~/EcsHud — the five layers end to end.
• CI improvements: samples compile job, samples gate (check_samples.py), real Unity test
  job, install probes, check_standalone.py wired into CI.
• A test that [UpdateInGroup] inherits onto a host's bridge subclass.

Fixed

• A sink registered mid-session received nothing until the simulation next wrote the component.
  The next pass after a registration now runs unfiltered exactly once.
• CI failed on its own dependency check after the com.gdk.core dependency was removed.
• check_standalone.py was never wired into CI.