Add headless regression tests for Phase 4b features

- Implement test for popup anchor behavior in rule-builder menus to ensure consistent anchor positioning during menu transitions.
- Create tests for stage logic, including mode transitions, toolbar visibility, and status bar updates.
- Add terrain drag-painting tests to verify correct block placement behavior and conflict handling.
- Introduce walk waypoint tests to check for arrival conditions and position stability after navigation.

scripts/stickman_library.gd

@@ -0,0 +1,67 @@
+class_name StickmanLibrary
+extends RefCounted
+
+const STICKMAN_FACTORY := preload("res://scripts/stickman_factory.gd")
+
+const STICKMEN_DIR := "res://stickmen"
+
+var entries: Array[Dictionary] = []
+
+
+func scan(dir_path: String = STICKMEN_DIR) -> Array[Dictionary]:
+	entries = _scan_dir(dir_path)
+	return entries
+
+
+func get_entries() -> Array[Dictionary]:
+	return entries
+
+
+func find_by_path(path: String) -> Dictionary:
+	for e: Dictionary in entries:
+		if String(e.get("path", "")) == path:
+			return e
+	return {}
+
+
+func make_entry(path: String) -> Dictionary:
+	var data: Dictionary = STICKMAN_FACTORY.load_stk(path)
+	if data.is_empty() or not data.has("body_parts"):
+		if not data.is_empty():
+			push_warning("StickmanLibrary: skipped '%s' (missing body_parts)." % path)
+		return {}
+	var name := String(data.get("stickman_name", "")).strip_edges()
+	if name.is_empty():
+		name = path.get_file().get_basename()
+	return { "path": path, "name": name, "data": data }
+
+
+func _scan_dir(dir_path: String) -> Array[Dictionary]:
+	if not DirAccess.dir_exists_absolute(dir_path):
+		push_warning("StickmanLibrary: stickmen dir '%s' not found." % dir_path)
+		return []
+	var dir := DirAccess.open(dir_path)
+	if dir == null:
+		push_warning("StickmanLibrary: failed to open '%s'." % dir_path)
+		return []
+	var files: Array[String] = []
+	dir.list_dir_begin()
+	var fname := dir.get_next()
+	while fname != "":
+		if not dir.current_is_dir() and fname.get_extension().to_lower() == "stk":
+			files.append(dir_path + "/" + fname)
+		fname = dir.get_next()
+	dir.list_dir_end()
+	var built: Array[Dictionary] = []
+	for path: String in files:
+		var entry := make_entry(path)
+		if not entry.is_empty():
+			built.append(entry)
+	built.sort_custom(func(a: Dictionary, b: Dictionary) -> bool:
+		var na := String(a["name"])
+		var nb := String(b["name"])
+		if na != nb:
+			return na < nb
+		return String(a["path"]) < String(b["path"])
+	)
+	return built