test:refression test for https://github.com/goplus/llgo/issues/1370

Co-authored-by: xgopilot <noreply@goplus.org>
Co-authored-by: Claude <noreply@anthropic.com>

cl/_testgo/interface1370/in.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	"github.com/goplus/llgo/cl/_testdata/geometry1370"
+)
+
+func main() {
+	rect := geometry1370.NewRectangle(5.0, 3.0)
+	geometry1370.RegisterShape(rect, 42)
+	println("ID:", rect.GetID())
+}