potential issue with large reads on nonframed messages

In tracking down an issue in an unrelated codebase, I discovered that at least in some cases, passing more than 2GiB to the pyca/cryptography `Cipher.update()` methods can cause issues with the underlying OpenSSL implementation.

This is not an issue with framed messages because our max frame size is 2GiB, but could be an issue for nonframed messages larger than 2GiB.

We should add tests that check for this edge case, and if it is an issue we can add chunking logic.

首先，將超過 2GiB 的資料傳遞給非分框訊息的 pyca/cryptography Cipher.update() 方法，以重現已回報的行為，並與分框訊息進行比較。為此邊界案例新增回歸測試；完成的標準是大型非分框訊息能可靠運作，並在確認底層 OpenSSL 問題後加入分塊邏輯。

由索引模型根據 Issue 內容生成。