feat: Add player movement manager, main scene, and backflip animation asset.

scenes/main.tscn

@@ -964,6 +964,7 @@ grow_horizontal = 0
 grow_vertical = 0
 
 [node name="ActionButtonContainer" type="VBoxContainer" parent="ActionMenu"]
+visible = false
 layout_mode = 0
 offset_right = 40.0
 offset_bottom = 40.0
@@ -974,11 +975,13 @@ layout_mode = 2
 text = "Move"
 
 [node name="GrabButton" type="Button" parent="ActionMenu/ActionButtonContainer"]
+visible = false
 custom_minimum_size = Vector2(100, 100)
 layout_mode = 2
 text = "Grab"
 
 [node name="PutButton" type="Button" parent="ActionMenu/ActionButtonContainer"]
+visible = false
 custom_minimum_size = Vector2(100, 100)
 layout_mode = 2
 text = "Put"

scripts/managers/player_movement_manager.gd

@@ -47,13 +47,17 @@ func simple_move_to(grid_position: Vector2i) -> bool:
 	if distance != 1:
 		return false # Only single-step moves allowed
 
+   	# Check if target position is within grid bounds
+	if not enhanced_gridmap.is_position_valid(grid_position):
+		return false
+
 	# Check for finish line logic (delegated back to player or race manager)
 	if player.has_method("can_move_to_finish") and not player.can_move_to_finish(grid_position):
 		return false
 
 	# Check walkability and obstacles
 	var cell_item = enhanced_gridmap.get_cell_item(Vector3i(grid_position.x, 0, grid_position.y))
-	if cell_item in enhanced_gridmap.non_walkable_items or player.is_position_occupied(grid_position): 
+	if cell_item == -1 or cell_item in enhanced_gridmap.non_walkable_items or player.is_position_occupied(grid_position):
 		return false
 	
 	if enhanced_gridmap.is_blocked_by_obstacle(player.current_position, grid_position, 3):
@@ -75,6 +79,10 @@ func move_to_clicked_position(grid_position: Vector2i) -> bool:
 	if not player.is_multiplayer_authority() or is_moving or player.action_points <= 0:
 		return false
 	
+	# Validate grid position is within bounds
+	if not enhanced_gridmap.is_position_valid(grid_position):
+		return false
+	
 	# Check finish line logic
 	if player.has_method("can_move_to_finish") and not player.can_move_to_finish(grid_position):
 		return false
@@ -122,9 +130,9 @@ func highlight_movement_range():
 				blocked_cells.append_array(enhanced_gridmap.get_cells_blocked_by_obstacle(cell_pos, orientation, 3))
 	
 	# Now highlight all cells within movement range that aren't blocked
-	for x in range(max(0, player.current_position.x - movement_range), 
+	for x in range(max(0, player.current_position.x - movement_range),
 				  min(enhanced_gridmap.columns, player.current_position.x + movement_range + 1)):
-		for z in range(max(0, player.current_position.y - movement_range), 
+		for z in range(max(0, player.current_position.y - movement_range),
 					  min(enhanced_gridmap.rows, player.current_position.y + movement_range + 1)):
 			var test_pos = Vector2i(x, z)
 			
@@ -171,18 +179,18 @@ func can_reach_cell(target_pos: Vector2i, blocked_cells: Array) -> bool:
 		
 		# Try all adjacent cells
 		var directions = [
-			Vector2i(0, -1),  # North
-			Vector2i(1, 0),   # East
-			Vector2i(0, 1),   # South
-			Vector2i(-1, 0),  # West
+			Vector2i(0, -1), # North
+			Vector2i(1, 0), # East
+			Vector2i(0, 1), # South
+			Vector2i(-1, 0), # West
 		]
 		
 		# Add diagonal directions if enabled
 		if enhanced_gridmap.diagonal_movement:
-			directions.append(Vector2i(-1, -1))  # Northwest
-			directions.append(Vector2i(1, -1))   # Northeast
-			directions.append(Vector2i(-1, 1))   # Southwest
-			directions.append(Vector2i(1, 1))    # Southeast
+			directions.append(Vector2i(-1, -1)) # Northwest
+			directions.append(Vector2i(1, -1)) # Northeast
+			directions.append(Vector2i(-1, 1)) # Southwest
+			directions.append(Vector2i(1, 1)) # Southeast
 		
 		for dir in directions:
 			var next_pos = current + dir