feat: Implement compiler and virtual machine for Fig language

- Added Compiler class with methods for compiling programs, statements, and expressions.
- Introduced Proto structure to hold compiled bytecode and constants.
- Implemented expression compilation including literals, identifiers, and infix expressions.
- Developed statement compilation for variable declarations and expression statements.
- Created a VM class to execute compiled bytecode with support for arithmetic and comparison operations.
- Added Object and Value classes for handling different data types and memory management.
- Implemented String and Struct objects for enhanced data representation.
- Established a parser for parsing variable declarations and statements.
- Included tests for the VM and object representations.

src/VM/VM.hpp

@@ -0,0 +1,75 @@
+/*!
+    @file src/VM/VM.hpp
+    @brief 虚拟机核心执行引擎
+    @author PuqiAR (im@puqiar.top)
+    @date 2026-02-19
+*/
+
+#pragma once
+
+#include <Compiler/Compiler.hpp>
+#include <Object/Object.hpp>
+#include <cassert>
+
+#include <iostream> // debug
+#include <print>
+
+namespace Fig
+{
+    class VM
+    {
+    private:
+        static constexpr unsigned int MAX_REGISTERS = 1024;
+
+        // 一次性分配
+        Value registers[MAX_REGISTERS];
+
+    public:
+        VM()
+        {
+            for (unsigned int i = 0; i < MAX_REGISTERS; ++i)
+            {
+                registers[i] = Value::GetNullInstance();
+            }
+        }
+
+    private:
+        inline OpCode decodeOpCode(Instruction inst)
+        {
+            return static_cast<OpCode>(inst & 0xFF);
+        }
+        inline std::uint8_t decodeA(Instruction inst)
+        {
+            return (inst >> 8) & 0xFF;
+        }
+        inline std::uint16_t decodeBx(Instruction inst)
+        {
+            return (inst >> 16) & 0xFFFF;
+        }
+        inline std::uint8_t decodeB(Instruction inst)
+        {
+            return (inst >> 16) & 0xFF;
+        }
+        inline std::uint8_t decodeC(Instruction inst)
+        {
+            return (inst >> 24) & 0xFF;
+        }
+
+    public:
+        // 执行入口：接收 Proto
+        Result<Value, Error> Execute(Proto *proto);
+
+        inline void PrintRegisters()
+        {
+            std::cout << "=== Registers ===" << '\n';
+            for (unsigned int i = 0; i < MAX_REGISTERS; ++i)
+            {
+                Value &v = registers[i];
+                if (!v.IsNull())
+                {
+                    std::println("[{}] {}", i, v.ToString());
+                }
+            }
+        }
+    };
+} // namespace Fig