feat: 添加取模运算符支持，更新解析器、解释器、词法分析器和相关示例以处理相关语法

src/lexer/token.rs

@@ -9,14 +9,14 @@ pub enum TokenKind {
     Colon,
 
     // 运算符
-    Plus, Minus, Star, Slash,
+    Plus, Minus, Star, Slash, Percent,
     Bang,
     Equal,
     Greater, GreaterEqual,
     Less, LessEqual,
     EqualEqual, BangEqual,
     AndAnd, OrOr,
-    PlusEqual, MinusEqual, StarEqual, SlashEqual,
+    PlusEqual, MinusEqual, StarEqual, SlashEqual, PercentEqual,
 
     // 字面量
     Identifier(String),