feat(audio): add tap handler and SFX to RoomChest

Adds _get_press_position helper and _unhandled_input tap detection to
RoomChest, wires AudioManager.play_sfx calls for chest_tap and
item_spawn events. Guards AudioManager audio load calls with Dummy
driver check so headless unit tests stay green.

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

scripts/objects/room_chest.gd

@@ -8,6 +8,7 @@ signal item_received(chest: RoomChest, item_id: String)
 const SPAWN_TWEEN_DURATION: float = 0.3
 
 @export var chest_id: String = ""
+@export var tap_radius: float = 50.0
 
 var _spawned_items: Array[HoldableItem] = []
 var _item_configs: Array[ChestItemData] = []
@@ -21,9 +22,22 @@ func _ready() -> void:
 			call_deferred("spawn_items")
 
 
+func _unhandled_input(event: InputEvent) -> void:
+	var press_pos: Vector2 = _get_press_position(event)
+	if press_pos == Vector2.INF:
+		return
+	var canvas_pos: Vector2 = get_viewport().get_canvas_transform().affine_inverse() * press_pos
+	if canvas_pos.distance_to(global_position) > tap_radius:
+		return
+	get_viewport().set_input_as_handled()
+	AudioManager.play_sfx("chest_tap")
+	spawn_items()
+
+
 func spawn_items() -> void:
 	if not _spawned_items.is_empty():
 		return
+	AudioManager.play_sfx("item_spawn")
 	var parent: Node = get_parent()
 	for config: ChestItemData in _item_configs:
 		var item: HoldableItem = _create_item(config)
@@ -71,6 +85,14 @@ func get_spawned_item(index: int) -> HoldableItem:
 	return _spawned_items[index]
 
 
+func _get_press_position(event: InputEvent) -> Vector2:
+	if event is InputEventScreenTouch and event.pressed:
+		return event.position
+	if event is InputEventMouseButton and event.pressed and event.button_index == MOUSE_BUTTON_LEFT:
+		return event.position
+	return Vector2.INF
+
+
 func _create_item(config: ChestItemData) -> HoldableItem:
 	var item: HoldableItem
 	if config.item_type == ChestItemData.ItemType.OUTFIT: