* fix: respect user mail deletion toggle in user center
Hide user mailbox delete actions and block /user_api/mails deletion when ENABLE_USER_DELETE_EMAIL is disabled. Add an e2e regression test and changelog entries for issue #978.
* test: hash user password in mail deletion e2e
Use the same SHA-256 pre-hashed password format as the frontend for the user register/login flow in the mail deletion regression test.
jiaxin