fix: 修改 Value::String 的显示格式，添加引号以增强可读性

src/interpreter/mod.rs

@@ -52,7 +52,7 @@ impl fmt::Display for Value {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             Value::Number(n) => write!(f, "{}", n),
-            Value::String(s) => write!(f, "{}", s),
+            Value::String(s) => write!(f, "\"{}\"", s),
             Value::Bool(b) => write!(f, "{}", b),
             Value::Nil => write!(f, "nil"),
             Value::Object(obj) => {