Implement Phase 17a Prop Roles UI/UX Specification and associated functionality

- Added UI/UX specification for prop roles and set down mechanics in phase 17a.
- Created `PropStageRoles` script to manage normalized behavior for props, including depth, motion, and collision settings.
- Introduced `StagePhysicsPolicy` for shared physics configurations related to props and actors.
- Developed comprehensive tests for prop roles, including default settings, legacy migration, serialization, and runtime behavior.
- Ensured proper handling of set down actions, including clearance and orientation preservation.

scripts/editors/stage/action_editor.gd

@@ -120,6 +120,13 @@ func set_throw_target(pos: Vector2) -> void:
 	popup_centered()
 
 
+func set_down_target(pos: Vector2) -> void:
+	_has_throw_target = true
+	_throw_target_pos = pos
+	_update_throw_target_label()
+	popup_centered()
+
+
 func current_action_type() -> String:
 	return _current_type()
 
@@ -294,14 +301,14 @@ func _rebuild_params(type: String) -> void:
 			var hand_idx := ["auto", "left", "right"].find(String(_initial.get("hand", "auto")))
 			_hand_option.select(maxi(hand_idx, 0))
 			hand_row.add_child(_hand_option)
-		"throw_prop":
+		"throw_prop", "set_down_prop":
 			var throw_row := HBoxContainer.new()
 			_params_box.add_child(throw_row)
 			_target_label = Label.new()
 			_target_label.size_flags_horizontal = Control.SIZE_EXPAND_FILL
 			throw_row.add_child(_target_label)
 			_set_target_btn = Button.new()
-			_set_target_btn.text = "🎯 Click target…"
+			_set_target_btn.text = ("📍 Change release place" if _has_throw_target else "📍 Choose release place") if type == "set_down_prop" else ("🎯 Change target…" if _has_throw_target else "🎯 Click target…")
 			_set_target_btn.pressed.connect(func() -> void: target_requested.emit())
 			throw_row.add_child(_set_target_btn)
 			_update_throw_target_label()
@@ -410,10 +417,11 @@ func _update_prop_target_label() -> void:
 func _update_throw_target_label() -> void:
 	if _target_label == null:
 		return
+	var label_prefix: String = "Release place" if _current_type() == "set_down_prop" else "Target"
 	if _has_throw_target:
-		_target_label.text = "Target: (%d, %d)" % [int(roundf(_throw_target_pos.x)), int(roundf(_throw_target_pos.y))]
+		_target_label.text = "%s: (%d, %d)" % [label_prefix, int(roundf(_throw_target_pos.x)), int(roundf(_throw_target_pos.y))]
 	else:
-		_target_label.text = "Target: not set"
+		_target_label.text = "%s: not set" % label_prefix
 
 
 func _on_ok_pressed() -> void:
@@ -434,7 +442,7 @@ func _on_ok_pressed() -> void:
 			var hands: Array[String] = ["auto", "left", "right"]
 			action["target_prop_id"] = _prop_target_id
 			action["hand"] = hands[_hand_option.selected] if _hand_option != null and _hand_option.selected >= 0 else "auto"
-		"throw_prop":
+		"throw_prop", "set_down_prop":
 			if not _has_throw_target:
 				target_requested.emit()
 				return

scripts/editors/stage/prop_settings_depth_cue.gd

@@ -0,0 +1,47 @@
+class_name PropSettingsDepthCue
+extends Control
+## Small vector picture showing whether a prop is drawn behind or in front.
+
+var _in_front: bool = false
+var _stickman_color: Color = Color("#F5F7FA")
+var _prop_color: Color = Color("#B7824D")
+var _outline_color: Color = Color("#171B24")
+
+
+func _ready() -> void:
+	mouse_filter = Control.MOUSE_FILTER_IGNORE
+	custom_minimum_size = Vector2(40.0, 34.0)
+	queue_redraw()
+
+
+func configure(in_front: bool, stickman_color: Color, prop_color: Color, outline_color: Color) -> void:
+	_in_front = in_front
+	_stickman_color = stickman_color
+	_prop_color = prop_color
+	_outline_color = outline_color
+	queue_redraw()
+
+
+func _draw() -> void:
+	if _in_front:
+		_draw_stickman()
+		_draw_prop()
+	else:
+		_draw_prop()
+		_draw_stickman()
+
+
+func _draw_prop() -> void:
+	var box := Rect2(Vector2(18.0, 10.0), Vector2(19.0, 19.0))
+	draw_rect(box, _prop_color)
+	draw_rect(box, _outline_color, false, 1.5)
+
+
+func _draw_stickman() -> void:
+	var head := Vector2(17.0, 5.5)
+	draw_circle(head, 4.0, _stickman_color)
+	draw_line(Vector2(17.0, 10.0), Vector2(17.0, 21.0), _stickman_color, 2.5, true)
+	draw_line(Vector2(17.0, 13.5), Vector2(9.0, 18.0), _stickman_color, 2.5, true)
+	draw_line(Vector2(17.0, 13.5), Vector2(25.0, 17.5), _stickman_color, 2.5, true)
+	draw_line(Vector2(17.0, 21.0), Vector2(11.5, 30.0), _stickman_color, 2.5, true)
+	draw_line(Vector2(17.0, 21.0), Vector2(23.0, 30.0), _stickman_color, 2.5, true)

scripts/editors/stage/prop_settings_depth_cue.gd.uid

@@ -0,0 +1 @@
+uid://dm8lgubovno3v