refactor(dev): 移动头文件位置

include/sem/SymbolTable.h

@@ -0,0 +1,17 @@
+// 极简符号表：记录局部变量定义点。
+#pragma once
+
+#include <string>
+#include <unordered_map>
+
+#include "SysYParser.h"
+
+class SymbolTable {
+ public:
+  void Add(const std::string& name, SysYParser::VarDeclContext* decl);
+  bool Contains(const std::string& name) const;
+  SysYParser::VarDeclContext* Lookup(const std::string& name) const;
+
+ private:
+  std::unordered_map<std::string, SysYParser::VarDeclContext*> table_;
+};