Step 337: Preprocessor AST Nodes (12/12 tests)

Added IncludeDirective, PragmaDirective, MacroDefinition as first-class AST nodes.
Full serialization roundtrip and CompactAST support. Preprocessor directives are
statement-level nodes with macro bodies kept as unparsed text.

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

editor/src/ast/PreprocessorNodes.h

@@ -0,0 +1,47 @@
+#pragma once
+#include "ASTNode.h"
+#include <string>
+#include <vector>
+
+// Preprocessor directive AST nodes — statement-level, added to Module children.
+// Preprocessor operates on text, not AST; macro bodies stay as unparsed text.
+
+class IncludeDirective : public ASTNode {
+public:
+    std::string path;       // "ast/ASTNode.h" or "string"
+    bool isSystem = false;  // angle brackets (true) vs quotes (false)
+
+    IncludeDirective() { conceptType = "IncludeDirective"; }
+    IncludeDirective(const std::string& id, const std::string& p, bool sys = false)
+        : path(p), isSystem(sys) {
+        this->id = id;
+        conceptType = "IncludeDirective";
+    }
+};
+
+class PragmaDirective : public ASTNode {
+public:
+    std::string directive;  // "once", "pack(push, 1)", etc.
+
+    PragmaDirective() { conceptType = "PragmaDirective"; }
+    PragmaDirective(const std::string& id, const std::string& dir)
+        : directive(dir) {
+        this->id = id;
+        conceptType = "PragmaDirective";
+    }
+};
+
+class MacroDefinition : public ASTNode {
+public:
+    std::string name;                    // Macro name
+    std::vector<std::string> parameters; // Empty for object-like macros
+    std::string body;                    // Unparsed macro body text
+    bool isFunctionLike = false;         // Has parameter list
+
+    MacroDefinition() { conceptType = "MacroDefinition"; }
+    MacroDefinition(const std::string& id, const std::string& n)
+        : name(n) {
+        this->id = id;
+        conceptType = "MacroDefinition";
+    }
+};