chore(client): add gdUnit4 test framework addon

Vendor gdUnit4 for Godot 4 client testing (D-030).

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

client/addons/gdUnit4/test/extractors/GdUnitFuncValueExtractorTest.gd

@@ -0,0 +1,66 @@
+# GdUnit generated TestSuite
+class_name GdUnitFuncValueExtractorTest
+extends GdUnitTestSuite
+
+# TestSuite generated from
+const __source = 'res://addons/gdUnit4/src/extractors/GdUnitFuncValueExtractor.gd'
+
+
+class TestNode extends Resource:
+	var _parent :TestNode = null
+	var _children := Array()
+
+	func _init(name :String, parent :TestNode = null) -> void:
+		set_name(name)
+		_parent = parent
+		if _parent:
+			_parent._children.append(self)
+
+
+	func _notification(what :int) -> void:
+		if what == NOTIFICATION_PREDELETE:
+			_parent = null
+			_children.clear()
+
+
+	func get_parent() -> TestNode:
+		return _parent
+
+
+	func get_children() -> Array:
+		return _children
+
+
+
+func test_extract_value_success() -> void:
+	var node :TestNode = auto_free(TestNode.new("node_a"))
+
+	assert_str(GdUnitFuncValueExtractor.new("get_name", []).extract_value(node)).is_equal("node_a")
+
+
+func test_extract_value_func_not_exists() -> void:
+	var node :TestNode = TestNode.new("node_a")
+
+	assert_str(GdUnitFuncValueExtractor.new("get_foo", []).extract_value(node)).is_equal("n.a.")
+
+
+func test_extract_value_on_null_value() -> void:
+	assert_str(GdUnitFuncValueExtractor.new("get_foo", []).extract_value(null)).is_null()
+
+
+func test_extract_value_chanined() -> void:
+	var parent :TestNode = TestNode.new("parent")
+	var node :TestNode = auto_free(TestNode.new("node_a", parent))
+
+	assert_str(GdUnitFuncValueExtractor.new("get_name", []).extract_value(node)).is_equal("node_a")
+	assert_str(GdUnitFuncValueExtractor.new("get_parent.get_name", []).extract_value(node)).is_equal("parent")
+
+
+func test_extract_value_chanined_array_values() -> void:
+	var parent :TestNode = TestNode.new("parent")
+	auto_free(TestNode.new("node_a", parent))
+	auto_free(TestNode.new("node_b", parent))
+	auto_free(TestNode.new("node_c", parent))
+
+	assert_array(GdUnitFuncValueExtractor.new("get_children.get_name", []).extract_value(parent))\
+		.contains_exactly(["node_a", "node_b", "node_c"])