feat: endless mode UI - game over card, best score, HUD

lib/state/game_session_notifier.dart

@@ -23,6 +23,7 @@ class GameViewState {
     required this.objectiveProgress,
     required this.lastPlacement,
     required this.fxTick,
+    required this.endless,
   });
 
   final GridState grid;
@@ -40,6 +41,8 @@ class GameViewState {
 
   /// Increments on every accepted placement so animations can retrigger.
   final int fxTick;
+
+  final bool endless;
 }
 
 /// Bridges the pure-Dart [GameEngine] to the widget tree. The engine object
@@ -107,7 +110,8 @@ class GameSessionNotifier extends Notifier<GameViewState?> {
       score: engine.score,
       comboStreak: engine.combo.streak,
       movesLeft: engine.movesLeft,
-      moveLimit: engine.movesLeft + engine.movesUsed,
+      endless: engine.endless,
+      moveLimit: engine.endless ? 0 : engine.movesLeft + engine.movesUsed,
       phase: engine.phase,
       stuckReason: engine.stuckReason,
       objectives: engine.objectives,