feat(engine): require N-key confirmation when abandoning an active game

Pressing N during an active game (move_count > 0, not won) now shows a
"Press N again to start a new game" toast and only starts a new game if
N is pressed a second time within 3 seconds. Starting a fresh game or
pressing N after a win still acts immediately.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_engine/src/animation_plugin.rs

@@ -11,6 +11,7 @@ use crate::auto_complete_plugin::AutoCompleteState;
 use crate::card_plugin::CardEntity;
 use crate::challenge_plugin::ChallengeAdvancedEvent;
 use crate::daily_challenge_plugin::{DailyChallengeCompletedEvent, DailyGoalAnnouncementEvent};
+use crate::events::NewGameConfirmEvent;
 use crate::events::{AchievementUnlockedEvent, GameWonEvent};
 use crate::game_plugin::GameMutation;
 use crate::layout::LayoutResource;
@@ -91,6 +92,7 @@ impl Plugin for AnimationPlugin {
             .add_event::<TimeAttackEndedEvent>()
             .add_event::<ChallengeAdvancedEvent>()
             .add_event::<SettingsChangedEvent>()
+            .add_event::<NewGameConfirmEvent>()
             .init_resource::<EffectiveSlideDuration>()
             .add_systems(Startup, init_slide_duration)
             .add_systems(
@@ -108,6 +110,7 @@ impl Plugin for AnimationPlugin {
                     handle_challenge_toast,
                     handle_settings_toast,
                     handle_auto_complete_toast,
+                    handle_new_game_confirm_toast,
                     tick_toasts,
                 )
                     .after(GameMutation),
@@ -310,6 +313,15 @@ fn handle_auto_complete_toast(
     }
 }
 
+fn handle_new_game_confirm_toast(
+    mut commands: Commands,
+    mut events: EventReader<NewGameConfirmEvent>,
+) {
+    for _ in events.read() {
+        spawn_toast(&mut commands, "Press N again to start a new game".to_string(), 3.0);
+    }
+}
+
 fn tick_toasts(
     mut commands: Commands,
     time: Res<Time>,