Expired sessions can still edit proposals

Sometimes faculty leave their tab open for a few days then come back to the application to submit. The form will still accept responses, even though their session is long gone.

The application should a) not do that, and b) not lose their progress because of a) being solved. In other words, let's save some of the data in cookies, and use sessions correctly.

先追蹤應用程式中的提案提交與工作階段驗證，然後找出表單資料在提交前的處理位置。確認工作階段過期時的預期行為，在要求重新驗證身分的同時保留已輸入的提案資料，並透過現有的應用程式流程驗證這兩種情況。

由索引模型根據 Issue 內容生成。