Add main menu scene with Rive UI, procedural background, and scene transitions

- Add Menu scene with Rive-driven login and navigation UI
  (RiveLoginController, RiveNavigationController) for entering a
  username and starting/navigating the client via Rive triggers
- Add SceneTransitionController to fade out and load the Landscape
  gameplay scene when Play is selected
- Add procedural low-poly triangle field background and animated wave
  panel (LowPolyTriangleField, TriangleWavePanel) with matching
  editor menus and materials
- Add MenuLightAnimator for animated menu lighting and UI fade helpers
  (MenuFadeIn, DebugFadeToggle/Bridge)
- Rename SampleScene to Landscape and wire ChatNetworkManager to hide
  the new Rive login canvas once gameplay starts
- Bump Input System action codegen version and add Rive package
  references/project settings updates to support the new UI

UserSettings/Search.settings

@@ -21,12 +21,15 @@ searchItemFavorites = [
 savedSearchesSortOrder = 0
 showSavedSearchPanel = false
 hideTabs = false
+indexOnEditorStartup = true
+logIndexingPerformanceReport = false
 expandedQueries = [
 ]
 queryBuilder = true
-ignoredProperties = "id;name;classname;imagecontentshash"
+ignoredProperties = "addedobjectfileids;classname;correspondingsourceobject;editorclassidentifier;editorhideflags;fileid;gameobject;id;imagecontentshash;isprefabvariant;name;objecthideflags;pathid;prefabasset;prefabinstance;script"
 helperWidgetCurrentArea = "all"
 disabledIndexers = ""
 minIndexVariations = 2
 findProviderIndexHelper = true
-itemIconSize = 32
+itemIconSize = 32
+version = 1