refactor: 重构 SnowExample 中的循环结构

- 将 loop 节点下的子节点名称从 initializer 改为 init
- 将 loop 节点下的子节点名称从 condition改为 cond
- 将 loop 节点下的子节点名称从 update 改为 step

src/main/java/org/jcnc/snow/pkg/utils/SnowExample.java

@@ -39,11 +39,11 @@ public final class SnowExample {
                         body:
                             declare num1: int = 1
                             loop:
-                                initializer:
+                                init:
                                     declare counter:int = 1
-                                condition:
+                                cond:
                                     counter <= n
-                                update:
+                                step:
                                     counter = counter + 1
                                 body:
                                     num1 = num1 * counter