fix(hierarchy): populate ResourceID from accessibilityIdentifier

iOS Compose surfaces testTag as accessibilityIdentifier. Previously
only resource-id and identifier seeded element.ResourceID, leaving
element.id empty for iOS Compose nodes and forcing specs to walk
attrs to recover stable identifiers.

internal/hierarchy/hierarchy.go

@@ -193,6 +193,9 @@ func elementFromNode(node *treeNodeJSON) *Element {
 	if element.ResourceID == "" {
 		element.ResourceID = attrs["identifier"]
 	}
+	if element.ResourceID == "" {
+		element.ResourceID = attrs["accessibilityIdentifier"]
+	}
 	element.Text = attrs["text"]
 	element.Description = attrs["content-desc"]
 	if element.Description == "" {

internal/hierarchy/hierarchy_test.go

@@ -514,6 +514,20 @@ func TestResourceIDFallsBackToAccessibilityIdentifier(t *testing.T) {
 	}
 }
 
+func TestElementResourceIDPopulatesFromAccessibilityIdentifier(t *testing.T) {
+	input := `{
+	  "attributes": {"accessibilityIdentifier": "LoginEmail", "bounds": "[0,0,100,100]"},
+	  "children": []
+	}`
+	tree, _ := Parse(input)
+	if len(tree.Elements) == 0 {
+		t.Fatal("no elements parsed")
+	}
+	if got := tree.Elements[0].ResourceID; got != "LoginEmail" {
+		t.Fatalf("ResourceID = %q, want LoginEmail (iOS Compose accessibilityIdentifier path)", got)
+	}
+}
+
 func TestNodeFindDoesNotReturnSiblings(t *testing.T) {
 	tree, _ := Parse(pathDump)
 	a2Node := tree.FindNode("id:A2")