feat: implement address deferencing

src/compiler/fzl_walker.c

@@ -942,6 +942,7 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
           fzl_token_t *tok = node->token;
           push_op(walker, FZL_OPCODE_PUSHNUM);
           push_word(walker, 0);
+          push_op(walker, FZL_OPCODE_DEREFERENCE);
           current_res = (fzl_walk_res_t){
               .type = FZL_TYPE_OBJECT, .error = false, .classname = null_name};
         }