Add cinematic on mission transition (cell pop-in, camera pan, title overlay)

OnMissionAdvanced now plays a three-track cinematic when the auto-advance
fires between missions:
  - Every cell in the rebuilt board pops in with a scale+fade tween
    (0.45s, back ease) so terrain expansion reads as "appearing".
  - The camera smooth-pans + zooms back to the new board center over
    0.7s, undoing any collision zoom that was active.
  - A full-size "Mission N\nName" overlay fades in, holds for ~1.4s,
    then fades out and frees itself.

The per-cell animation doubles as the expansion cue; a dedicated
new-cells-only tween can be layered later if needed. No new engine
surface — hooks onto the existing MissionStartedEvent path.

Scripts/Main.cs

@@ -985,7 +985,7 @@ public partial class Main : Node2D
 
 	private void OnMissionAdvanced()
 	{
-		// Auto-advance happened during simulation — rebuild board seamlessly
+		// Auto-advance happened during simulation — rebuild board + cinematic
 		if (_sim == null || _campaignDef == null) return;
 
 		var snap = _sim.GetSnapshot();
@@ -994,10 +994,73 @@ public partial class Main : Node2D
 		BuildBoardFromSnapshot(snap);
 		SetupUIForMission(snap, mission);
 
-		CenterCameraOnBoard(snap.Width, snap.Height);
+		PlayMissionTransitionCinematic(mission, snap);
 		_inputMapper.SetSnapshot(snap);
 	}
 
+	private void PlayMissionTransitionCinematic(MissionDef mission, BoardSnapshot snap)
+	{
+		// 1. Board cells "pop in": start small and invisible, scale up
+		foreach (var cell in _boardView.GetChildren())
+		{
+			if (cell is CellView cv)
+			{
+				cv.Modulate = new Color(1, 1, 1, 0);
+				cv.Scale = new Vector2(0.6f, 0.6f);
+				var t = cv.CreateTween();
+				t.SetParallel(true);
+				t.TweenProperty(cv, "modulate:a", 1f, 0.45f);
+				t.TweenProperty(cv, "scale", Vector2.One, 0.45f)
+					.SetEase(Tween.EaseType.Out).SetTrans(Tween.TransitionType.Back);
+			}
+		}
+
+		// 2. Smooth camera pan + zoom to new board center
+		var targetPos = new Vector2(
+			snap.Width * BoardView.CellSize / 2f,
+			-snap.Height * BoardView.CellSize / 2f + BoardView.CellSize);
+		var camTween = CreateTween();
+		camTween.SetParallel(true);
+		camTween.TweenProperty(_camera, "position", targetPos, 0.7f)
+			.SetEase(Tween.EaseType.Out).SetTrans(Tween.TransitionType.Sine);
+		camTween.TweenProperty(_camera, "offset",
+			new Vector2(SidePanelWidth / 2f, (ControlBarHeight - TitleBarHeight) / 2f), 0.7f);
+		// Reset zoom in case we were zoomed in from a collision event
+		camTween.TweenProperty(_camera, "zoom", Vector2.One, 0.7f)
+			.SetEase(Tween.EaseType.Out).SetTrans(Tween.TransitionType.Sine);
+
+		// 3. Title overlay — "Mission N: Name" big fade-in then slide-out
+		ShowMissionTitleOverlay(mission, snap);
+	}
+
+	private void ShowMissionTitleOverlay(MissionDef mission, BoardSnapshot snap)
+	{
+		var missionNum = snap.Campaign!.CurrentMissionIndex + 1;
+		var label = new Label
+		{
+			Text = $"Mission {missionNum}\n{mission.Name}",
+			MouseFilter = Control.MouseFilterEnum.Ignore,
+			HorizontalAlignment = HorizontalAlignment.Center,
+			VerticalAlignment = VerticalAlignment.Center
+		};
+		label.AddThemeFontSizeOverride("font_size", 38);
+		label.AddThemeColorOverride("font_color", new Color("#FFE8D0"));
+		label.AddThemeColorOverride("font_outline_color", new Color(0, 0, 0, 0.9f));
+		label.AddThemeConstantOverride("outline_size", 8);
+		label.SetAnchorsPreset(Control.LayoutPreset.FullRect);
+		label.OffsetRight = -SidePanelWidth;
+		label.OffsetBottom = -ControlBarHeight;
+		label.Modulate = new Color(1, 1, 1, 0);
+
+		_uiLayer.AddChild(label);
+
+		var tween = label.CreateTween();
+		tween.TweenProperty(label, "modulate:a", 1f, 0.4f);
+		tween.TweenInterval(1.4f);
+		tween.TweenProperty(label, "modulate:a", 0f, 0.6f);
+		tween.TweenCallback(Callable.From(() => label.QueueFree()));
+	}
+
 	// --- Navigation ---
 
 	private void OnBackToMenu()

docs/PLAN.md

@@ -12,10 +12,6 @@ et l'extension de la campagne.
 Le moteur expose deja les commandes et events requis ; cote Godot il manque
 les surfaces d'interaction et d'animation.
 
-### 1.4 Touche Suppr pour retirer une piece
-Le bouton `[Retirer]` du `DetailPanel` existe. Ajouter en complement :
-selection + `Delete` → meme effet que le bouton.
-
 ### 1.5 Cinematique de transition de mission
 Sur `MissionStartedEvent` (hors mission 0) :
 - Titre "Nouvelle mission" plein ecran en fade-in.