feat: Add stdlib_core.c to centralize standard library module registration and define core native functions like len, list_push, list_pop, and substr.

Author: ProgrammerKR

src/stdlib/stdlib_core.c

@@ -32,8 +32,12 @@ extern Value native_clock(int argCount, Value* args);
 
 static Value native_len(int argCount, Value* args) {
     if (argCount < 1) return NUMBER_VAL(0);
+    // printf("native_len: Type=%d, IS_LIST=%d, IS_STRING=%d\n", AS_OBJ(args[0])->type, IS_LIST(args[0]), IS_STRING(args[0]));
     if (IS_STRING(args[0])) return NUMBER_VAL((double)AS_STRING(args[0])->length);
-    if (IS_LIST(args[0])) return NUMBER_VAL((double)AS_LIST(args[0])->count);
+    if (IS_LIST(args[0])) {
+         // printf("It is a list! Count: %d\n", AS_LIST(args[0])->count);
+         return NUMBER_VAL((double)AS_LIST(args[0])->count);
+    }
     if (IS_MAP(args[0])) return NUMBER_VAL((double)AS_MAP(args[0])->count);
     return NUMBER_VAL(0);
 }