Step 121: add import/external module AST concepts

editor/src/ast/ExternalModule.h

@@ -0,0 +1,19 @@
+#pragma once
+#include "ASTNode.h"
+
+class ExternalModule : public ASTNode {
+public:
+    std::string name;
+    std::string version;
+    std::string language;
+
+    ExternalModule() { conceptType = "ExternalModule"; }
+    ExternalModule(const std::string& id, const std::string& name,
+                   const std::string& language,
+                   const std::string& version = "")
+        : name(name), version(version), language(language) {
+        this->id = id;
+        this->conceptType = "ExternalModule";
+    }
+    // children: signatures (0..n) via addChild("signatures", TypeSignature*)
+};