feat: Implement draggable torso and head IK targets in the test harness

- Added draggable handles for the torso and head to the test harness.
- Updated `IK_HANDLE_PATHS` to include new entries for "Head" and "Torso".
- Implemented distinct colors for the torso (magenta) and head (yellow) markers.
- Added a visual aid (aim line) to indicate the head's LookAt target direction.
- Ensured that dragging the torso moves only the torso marker, allowing for limb stretching towards stationary targets.

scripts/stickman_editor.gd

@@ -48,10 +48,10 @@ const DEFAULT_POSITIONS: Dictionary = {
 	"right_lower_leg": Vector2(165, 210),
 }
 
-const FILE_VERSION := "1.4"
+const FILE_VERSION := "1.5"
 const FILE_FILTER := "*.stk ; Stickman Files"
 
-const SUPPORTED_VERSIONS: Array[String] = ["1.0", "1.1", "1.2", "1.3", "1.4"]
+const SUPPORTED_VERSIONS: Array[String] = ["1.0", "1.1", "1.2", "1.3", "1.4", "1.5"]
 
 # Phase 8: rig proportions (master_rig.tscn rest pose — see spec §2).
 const PROPORTIONS: Dictionary = {
@@ -66,6 +66,22 @@ const X_AXIS_PARTS: PackedStringArray = [
 	"left_upper_arm", "left_lower_arm", "right_upper_arm", "right_lower_arm",
 ]
 
+# Phase 9 Round 5: map each body part to its silhouette-guide joint (see
+# whole_stickman_preview.gd GUIDE_JOINTS). Used to compute the per-part
+# guide_offset (bbox center − guide joint, preview space) at save time.
+const GUIDE_JOINT_FOR_PART: Dictionary = {
+	"head": "Neck",
+	"torso": "Hips",
+	"left_upper_arm": "LeftShoulder",
+	"left_lower_arm": "LeftElbow",
+	"right_upper_arm": "RightShoulder",
+	"right_lower_arm": "RightElbow",
+	"left_upper_leg": "Hips",
+	"left_lower_leg": "LeftKnee",
+	"right_upper_leg": "Hips",
+	"right_lower_leg": "RightKnee",
+}
+
 const SETTINGS_PATH := "user://settings.json"
 const SETTINGS_VERSION := "1.0"
 const DEFAULT_GRID_SIZE := 15
@@ -413,6 +429,9 @@ func _collect_all_shape_data() -> Dictionary:
 			var rot := _whole_preview.get_part_rotation(part_name)
 			var scl := _whole_preview.get_part_scale(part_name)
 			var pl := _compute_part_pivot_length(shapes_arr, part_name)
+			var pivot_vector := Vector2(float(pl["pivot"]["x"]), float(pl["pivot"]["y"]))
+			var joint_preview := _whole_preview.get_guide_joint_preview(GUIDE_JOINT_FOR_PART[part_name])
+			var guide_offset := (pos + pivot_vector) - joint_preview
 			all_data[part_name] = {
 				"shapes": shapes_arr,
 				"position": {"x": pos.x, "y": pos.y},
@@ -420,6 +439,7 @@ func _collect_all_shape_data() -> Dictionary:
 				"scale": {"x": scl.x, "y": scl.y},
 				"pivot": pl["pivot"],
 				"length": pl["length"],
+				"guide_offset": {"x": guide_offset.x, "y": guide_offset.y},
 			}
 	return all_data
 
@@ -449,7 +469,7 @@ func _apply_json_data(json: Variant) -> String:
 
 	var version: String = dict.get("version", "")
 	if version not in SUPPORTED_VERSIONS:
-		return "Unsupported file version: '%s' (expected '1.0', '1.1', '1.2', '1.3', or '1.4')" % version
+		return "Unsupported file version: '%s' (expected '1.0', '1.1', '1.2', '1.3', '1.4', or '1.5')" % version
 
 	_stickman_name_edit.text = dict.get("stickman_name", "")